I found this hack on YouTube by a kid named Ray, who shows you how to download and install paid apps for free. Of course, it’s probably illegal and we highly recommend to buy your apps and it’s informational purposes ONLY!
Basically what you do is do a Google search for any .apk files. For example, if you wanted an app called Picaso (just making it up), do a Google search for Picaso.apk.
Download the apk file, copy it to your phone’s SD card, then use apkInstaller to install it, and voila!
This should work the same on any kind of Android-based phone including Nexus One, Droid, and etc…etc…
You can also read How to Install .Apk Files on your Android Phone for more clear directions.