Here is how it works:

First you need to follow @gcal on Twitter, After that, you need to grant Twittercal a permission to access your Google Calendar account. Once you have done that, you can start adding events to your Google Calendar by sending direct messages.

For example, sending “d gcal meet Elisha at Mcdonald’s tomorrow at 10 a.m.” will add “meet Elisha at Mcdonald’s tomorrow at 10 a.m.” to your schedule. It’s that easy.

Features:

• Add events to your Google Calendar from your favorite Twitter client.
• Really easy to get started.
• No registration needed, free.

Check out Twittercal @ www.twittercal.com (by Srikanth AD from Techonaut)

The only thing you should keep in mind is that in order for GooSync to keep your Google and phone calendars synced it needs to be abe to continuously connect to the internet. So unless your mobile phone plan has an unlimited data plan, you might end up with a hefty sum on your phone bill.

Features:

• Synchronize your Google Calendar with Blackberry, iPhone or almost any other cell phone.
• Supports 100′s of mobile phone, see the full list of supported mobile phone models here.
• Free account lets you sync appointments upto 30 days in advance.
• Bi-directional calendar synchronization.
• Google Apps Support: Synchronize your device with your Google Apps Calendar.
• Premium account with more options is also available.

Check out GooSync @ www.goosync.com

Features

• Launch favorite web apps with a single click and keep them minimized on the Taskbar.
• Run Web application like any other desktop program.
• Default Bubbles Apps: Gmail, Google Calendar, 30 Boxes, SlimTimes, Yahoo Mail and Flickr.
• Trun any website or service to Bubbles App. It can be Digg, Del.icio.us, your WordPress blog, anything.
• Set “Bubbled” apps to launch and get minimized to taskbar on Windows start-up.
• Note : At the moment Bubbles available only to Windows users (2K, XP and Vista).

As mentioned above, Bubbles already comes with a number of preconfigured services and all you need to do is enter login details. However apart from bringing these services to your desktop, Bubbles also adds a number of cool features:

• Google calendar notifier: Get instant desktop notifications for upcoming events.
• Gmail / Yahoo email Notifier: Get instant desktop-notifications for new email.
• Flickr Uploader: Upload photos by dragging them on top of Flickr Bubble.
• Quick shortcuts to frequently accessed locations for each app.

Check out Bubbles @ www.3d3r.com/bubbles/ [via Online Tech Tips]

AuctionReminder Features / Requirements

• Choose how long before an auction ends you should be reminded.
• Get reminders via email, pop-ups, or SMS (geo restrictions apply).
• Add auction items using it’s web URL or eBay item number.
• You need to have Google Calendar account and authorize AuctionReminder to access your calendar.
• Browser bookmarklet: Add auctions directly from the auction page.
• Supported eBay sites: ebay.com (USA), ebay.co.uk (United Kingdom), ebay.com.au (Australia).
• More information can be found on AuctionReminder’s help page.

Go to AuctionReminder @ [www.auctionreminder.net]

Features:

• View calendar by day/week/month/…
• Create multiple calendars and share them with others (coworkers, friends, family, etc)
• Let others not only view but also add entries to your calendar. Very convenient for project teams
• Upcoming Event reminders: get notified by email OR mobile text messages
• Subscribe to calendars of others and view next to your own
• Well-implemented Gmail integration
• Search Calendars
• Natural language event entry: Typing ‘dinner on March 13 with Susan’ will create ‘dinner with Susan’ on March 13
• and more …
• Demo Tour

Visit Google Calendar