I got this from other people and its true. so try it it works.

All Android phones have WIFI capabilities...turn on WIFI on your phone, connect to the network and you can go to the market and download your apps. Wouldn't that be easier to download apps

I think this tip is better for people who cannot access some type of apps, like paid ones, on the market.

Or, if you only have the .apk on your computer, upload it to dropbox, open dropbox app on android, click file, install.

No need to connect the phone to the computer.