This is a great way to install applications without connect directly the phone to the computer
1. Create a Dropbox account (if you already has it, skip this step)
2. Download and install Dropbox in your phone
3. Put the apk file in the dropbox
4. Open the apk file in your mobile phone
Pay attention to the synchronization. Make sure that the application that you are installing is the newest cause it can indicate when was it uploaded.