When you're creating a smart home, you'll spend most of your time thinking about things that are within the walls of your house, like smart lamps and smart TVs. But there are some really cool things you can do when you're outside, too! One of those things is unlocking your front door -- why not take keys out of the equation and use a smarter solution? Here are 5 different locks that you can unlock with your phone.

August Smart Lock

The August lock, though it isn't out yet, provides a lot of great options in a small package. It's easy to install (it only requires a screwdriver and a few AA batteries), it doesn't need WiFi or power from your house, it uses Bluetooth to automatically unlock your door when you approach with your smartphone, and it'll even lock the door behind you when you leave.

August gives you a lot of control over access to your home as well -- you can send invitations to other users of the August app, and they'll be able to use the app to unlock your door. Those invitations can be extended for a limited amount of time, so you don't need to worry about canceling your house sitter's access to your house. You can even get notifications when someone unlocks the door, so you'll know if your friends from out of town showed up.

A lot of people will be concerned about replacing their keys with their phone; what if you lose your phone, or you're out of battery? August only replaces the interior part of your deadbolt, so you can always use your keys outside. And because you open the lock with an app, you can download the August app on someone else's phone, sign in, and open the lock.

You can pre-order the August smart lock for $199, with a projected shipping date of "2014."

Lockitron Smart Lock

Lockitron offers a number of the same features as the August smart lock, though in a slightly different package. The lock itself is much larger on the inside, though it includes a physical lock switch, much like the one you probably already have on the door. The Lockitron actually fits over your existing lock instead of replacing it, and the motor inside just turns your already existing lock. The outside of the lock isn't affected, so you can still use your keys.

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You can issue permissions for others to be able to lock your door, and you can also receive notifications when the door is locked or unlocked to monitor your home security. Although the lock is operated via Bluetooth or Near-Field Communication, it can also connect to your home WiFi, allowing you to lock or unlock your door from a distance. You can also connect the lock to IFTTT, giving you a number of options for allowing access to your front door.

The Lockitron app looks to be very slick and easy-to-use, with simple lock and unlock controls. The lock isn't shipping yet, though it's supposed to be out sometime this fall at $179. Lockitron promised to ship a lot of these units after an extremely successful Kickstarter campaign, but as of January, a lot of backers were still waiting to receive their lock. Might be best to wait until it's actually released to place an order. If you don't want to wait, you can get the first edition of the lock from Amazon for $299.

Kwikset Kevo Smart Lock

One of the manufacturers on this list that you might recognize, Kwikset has been making high-quality locks for a long time, and the name has a great deal of credibility. The Kevo, their entry into the smart lock game, is a really cool piece of equipment that combines the familiarity of a normal deadbolt with the ease of a smart lock.

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The Kevo lock looks just like any other Kwikset lock, except for the light-up blue circle around the inside edge, which illuminates when the lock is used. If you have your iPhone (there's no Android option yet) or the included key fob close to the door, all you have to do is tap the lock and it'll open. You can give others temporary access -- all they have to do is download the Kevo app (you can also purchase additional fobs that you could give to neighbors or friends). And, of course, there's always the option to just use the key.

Kevo locks come with two free eKeys that will allow access to the lock. Additional keys can be purchased for $1.99 each, and provide unlimited access for a single user; guest keys are free. The lock itself is $219 on Amazon.

Goji Smart Lock [No Longer Available]

The Goji lock is a bit different than the others on the list, as it's meant to be more of a home security device than just a lock. This is evident in the fact that it gives you the ability to see who's at the door from your cell phone before going to let them in. Pictures of visitors are logged in the mobile app, so you can see who's been at your door whether you're at home or not.

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Goji also makes fobs that you can clip to your keychain, backpack, purse, or other item so you can get back into your house without your phone. The lock also comes with two metal keys that you can use as backups should you not be able to use either of the other methods. And, like the other locks in the list, you can give temporary access to others via the app.

You'll notice that Goji has a screen on the lock that will welcome you home when you return; while this doesn't have a practical purpose, it does add to the cool, futuristic look of the device. The interior of the lock looks a bit like the Lockitron. The Goji lock is available in the silver, copper, and gold finishes, and can be purchased for $278 from the Goji website. Fobs for the lock are $40 each.

Danalock Smart Lock [No Longer Available]

One of the most affordable smart locks, the Danalock can be yours for only $159. This lock comes in Bluetooth and Z-Wave versions, as well as one that works with both, so you can get a lock that works for your home system. It provides the same benefits that most others locks do; guest access, logs, locking and unlocking from anywhere, and automatic re-lock.

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An interesting feature of the Danalock is that it can be connected to other systems, making it a viable option for businesses, hotels, and other professional applications. While the aesthetics of the lock don't quite stack up to those of the other locks on the list, this is a versatile and very affordable option.

Interestingly, the Danalock website says that it's ready for shipment, but Amazon still lists is as a pre-order. This could be concerning for interested customers; we'll just have to wait and see how it goes.

Start Smartening Your Locks!

Door locks are a great place to start smartening your home, and they can be set up with minimal effort and time. Most of them just screw onto your door in place of your regular lock. And there are plenty of options out there—while these five are some of the most popular right now, the marketplace is rapidly expanding, and we're likely to see a lot more options in the near future.

As smart locks become more popular, it's likely that we'll start hearing about their security merits and drawbacks, much like we have with smart TVs. There are a number of sites online that fall on both sides of this argument, so we'll be looking forward to more stringent testing.

Have you used a smart lock? How did you find it? Do you feel nervous about a Bluetooth-enabled lock? Share your thoughts below!

Image credit: Businessman selecting a white padlock with world map on the background (edited) via Shutterstock