Install .apk on android phone
You can also place an .apk file on a web server and then using the built-in web browser on your android phone, navigate to that URL which will cause the browser to download the apk file. You will then have the ability in the downloads window to click on the downloaded apk file which Android will then try to install.

I forgot to mention to make sure the content-type is:

Content-Type: application/vnd.android.package-archive