There are lots of memory booster apps on the Google Play Store , but which apps of the lot would you recommend in terms of functionality and quality?
Smart Memory Booster (free app, no ads)- https://play.google.com/store/apps/details?id=droidmate.membooster
My favorite is ES Task Manager, but I haven't really had to use it ever since I moved to the Almighty MIUI rom :D
Memory Booster apps do not work the same way they do on a PC. Android handles memory differently than a PC does.
Go Launcher EX has a memory cleanup app built into it if you use it as your default launcher.
There are some memory booster Apps avialble like, Memory Booster - RAM Optimizer, Super Booster-Memory Optimizer, Memory Booster (Full Version), etc. These Apps have good user rating and high popularity. It is better to try some apps by yourself and find the best one based on your requirements and easy to use interface- http://goo.gl/GSJ5M.
I really like Auto Memory Manager By Mad Squirrel it's very easy to configure and customize it runs on rooted and unrooted devices for $1.59 you can get the app without any ads if you don't mind the ads then it's yours for free. Here's a link if you want to check it out.