Google Voice is a phone service provided by the makers of Gmail. It is an extremely well priced and competitive phone service that has VoIP rates which are literally pennies. In fact, if you are in the USA then calls are completely free throughout North America. The service also offers a number of other perks, such as voice transcription, conference calls, SMS to email, voicemail and even voicemail message to email services.
MobiGater is a device which transfers your Skype calls to your mobile phone without the use of SkypeOut credits. It connects to your cell phone via a SIM card placed inside it, and using a USB cable to your PC and Skype.