Camera: Possibly my saddest realization once I got my andriod was that instagram isn't compatible with andriod yet. They are working on making it for andriod but until then, here are some that are pretty cool too.
-Retro Camera (free). You get to choose between six different types of toy cameras. This is the camera app I use the most. It's super user friendly and comes out with great pictures. In nearly all of my instagram type posts this is the app I use.
-FX Camera (free). I personally love the "polandriod" camera option, but there are also a toycam, fisheye, symmetriCam, and Warhol options. The only downside to both of these camera apps is in both of them you have to pick which option you want then take the picture, you can't edit a picture you've already taken.
Games: I am the type of person who get's sucked into a game once I start, therefore I try my hardest to only have a few game on my phone. Right now Draw Something is my favorite I just downloaded it a few days ago and I'm already hooked. If you can't draw don't fear, I can't either, but it's still fun to try to draw and guess what your friends were thinking.
Reading: The Amazon Kindle app. I try to only download one book at a time so that I don't feel overwhelmed. So far I've read, Alice in Wonderland, And my favorite fairy tales from the Grimm Brothers (they are much different than the Disney versions, be warned).
Other: I was sitting on my bus one day and felt like learning Italian so I searched the app store and found one by Busuu. It's pretty good, the only downside is it picks up rather quickly so if you stop using it for a month or so and go back you may have to refresh your memory.
What are your favorite apps?