GVNotifier is a free Windows application that brings Google Voice to your desktop.
GVNotifier is simple and compact, but still full feature desktop client for Google Voice. With GVNotifier you will be able to send and recieve SMS messages, listen and read voicemail messages, view all your Google Voice contacts, and all your call history right from your taskbar. It also has Windows 7 jump list and progress indicator support.
To make a call or to send a SMS you just need to click on the taskbar icon and it will bring up your recent contacts in a small screen with the options. You can also right click on the icon to bring up a separate window from where you can dial a phone number, if the desired contact is not in the recent call list.
When you receive a SMS, GVNotifier pops up a little window from where you can read the SMS as well as send a reply right away.
You can even make GVNotifier portable if you want. To do so, copy the application files to your USB flash drive and create a blank text file named settings.xml in the same directory as GVNotifier.net.exe. GVNotifier will then store all preferences and cached contact photos in the same directory.
GVNotifier works on Windows 7/Vista/XP but requires .Net 3.5 framework.
Download: GVNotifier [direct-link] | Microsoft .NET Framework 3.5 SP 1