For those of you leaving on the edge of your Windows Phone 7 software (e.g. Google Maps, ringtone manager), you would be a little experienced with installing .XAP files (pronounced "zap") which are basically the WP7 version of .CABs. While installing them isn't that hard (Start Menu --> Windows Phone Developer Tools --> Application Deployment --> Select file), looks like someone wanted to make it even easier.
If you remember the old add on .cab installer for Windows Mobile called CabViaActiveSync, this app by Tom Condon should be very familiar: it basically allows one-click install of any .xap file on your computer. Simply download the zip, extract the .exe and Run As Administrator. Now, whenever you click on a .xap file, you'll get the above dialog screen allowing direct installs to the phone.
While many of you haven't unlocked yet and the Homebrew scene is still in its infancy, we recommend you bookmark this or make a mental note as this app will be very useful later on.
Source: XDA Forums