I've been trying to cut the strings w/Ma Bell for the past year for home phone service and have tried MagicJack and Ooma but didn't like having a computer on 24/7 for MagicJack and I'm a bit uncomfortable w/Ooma being around for the long haul. Since then I've been using a Linksys SPA3102 with cobbled together free service using Sipgate for the outbound & Google Voice for the inbound.
Just stumbled on the Obi110 on Amazon for $50 which directly interfaces with Google Voice for free US inbound/outbound calling. Uses standard phone/fax dialing.
It has a FXS & FXO port and you can bridge between the two, nice for use out of the country too for calling relatives or making local calls at the remote.
Got it a few days ago & it's working great, easy to set up & good quality voice over free Google Voice. Google has confirmed that their service will be free at least for 2011 but I'd suspect they would receive a bunch of blowback if they decided to charge a lot for the service going forward.
Setup guide at:
[No affiliation w/Obi or Google, just a happy user]