Adobe AIR: If you'd like to keep quick access to your Google Voice voicemail and SMS messages handily in place on your dock or taskbar, a cross-platform app gives you exactly that by packaging up Google Voice's mobile site.
Just like on a mobile browser, Voice's interface is surprisingly spry for such a pared-down site, but it's also lightning fast running on a desktop or laptop. The app allows you to play and pause voicemail messages through your system's audio, set up calls with your hooked-up phones, and run through your contacts and search your SMS and transcription history. With Google Voice no longer requiring a new number, this little app might be a nice introduction to the service for those who don't want to commit to keeping a browser tab open all day.
Google Voice Desktop is a free download, works on any system with Adobe AIR installed.