If you have been living in US, you must have been a user of the Google’s voice chat service called Google Voice. For others who don’t know what Google Voice is, it is a free service by Google that enable the users to call and have voice chat.
Google Voice provides you with a single number that enables you to be in touch anywhere. Using this, you can also get voicemail into your inbox. It also provides you free calls to US and Canada while cheap to other places. To use this service, you need to sign up with Google Voice and in case you are already an existing user then it must have been very irritating for you to log in again and again on the website to use the service.
Thus there is the desktop Google Voice client called GVNotifier which you can use for the same purpose. GVNotifier is a powerful app that brings Google Voice right to your Windows desktop. Using this, you can send or receive messages, listen to or read voicemail, connect calls, access address books, see history and more.
Moreover the tool is free and portable to use. You just need to copy all the files in the installation directory to a folder in the USB drive and create a blank file settings.xml in the same folder where the files are copied; it will become a portable app from now on. You can also some shortcuts on this tool, about which you can read more at the link below.
P.S.: Since Google Voice is currently available in US, the tool shall work only for the US users at the moment.