I found that there are many many great android apps were not in the android market, but actually I still able to install them into my android phone with certain way. There are 3rd party application which are not recognize in android market OR they need to be independent from Android market. Anyway, you still may able to download them and use it in your android phone. How??
Download your desire *.apk file from any website to your pc. Transfer the file to your SD card. How to transfer? Follow this post.
By default, your android phone was not allow any 3rd party application installation. So, you need to enable it manually.
Goto-> Setting –> Applications –> Unknown sources. Check on the unknown sources to allow installation of non-Market applications. Click continue if you see warning (warning is about now you have more chances to let the 3rd party access to your phone). Well, you have completed second steps.
Use any file manager in your android phone (ASTRO, ES file explorer.. you may need to install them first before you install the 3rd party apps) to access to the apk you have stored in your android phone in the very first place. Double click on the apk files, you will be directed to install the 3rd party applications. Done…
You can now enjoy your 3rd party applications on your android phones… It works perfectly in my Nexus S.