1. AirDroid: this one is one of my favorites it allow you to transfer files over the air via a network at your home or office in a secure way. It gives an address to make a connection and once connected you can exchange files and can even send messages right from your Browser, give it a try it will change the way you transfer files, as in my case.
2. Instagram: it recently hit Android and is even bought by Facebook, it allows users to share photos and also applies those cool filters, if you are still not using it better download.
3. Twicca: Twicca is a classic twitter client which is free and without ads and has got good enough functions to be your go to twitter app on your Android. I like it because it has got an option to put the cache in external storage which is very helpful sometimes and it also has a nice option to colour tag people you follow so you get the colour in front of their tweets.
4. QuickPic: It is an alternate to the default Gallery of Android which gives a neat and more better interface for listing your videos and images and also has got the option of switching the view between grid and list.
5. Moon+ reader: Now this one is more like a copy of iBooks but this one is cool and if you are a fan of reading books on your phone like I am this is a must have app. It has got those cool page transitions and a good list of backgrounds to choose.
Download Moon+ reader