these are some best sites from where u can download Andriod Apps :
AppBrain aims to help you find the best Android apps downloads. They do this by giving you the ability to browse apps based on rankings, reviews, and categories. They also give you the chance to see app statistics such as costs, free vs paid, storage space, and categories.
AppGuide is part of the PCWorld.com group of sites. You can browse by category as you can on most app sites. But here, you get the benefit of editor reviews. The editors from PCWorld.com routinely give expert reviews. Mixed in with these editor reviews are reviews from users as well.
3-Appolicious (in association with Yahoo!)
When connected to Facebook, Applicious will recommend apps that your friends are using.
Aproov gives you filtering by category and the ability to search. Aproov has their own algorithim called App Rank to filter apps to the top of lists based on several rankings.