Things I didn't know existed until just recently: the Obihai OBiTalk, a gizmo that plugs into your router and pairs with SIP-based voice-over-IP services like Google Voice; and GVJack App, a Windows utility that links a MagicJack to your Google Voice account.
Why are these products significant? Simple: Google Voice offers free local and long-distance calling -- through the end of 2012, at least. After that, it's anybody's guess. Google might continue the free-phone goodness, or it might start charging for service. (If the latter happens, it's a good bet it'll be cheap.)
Whatever the case, GVJack App offers an intriguing solution for inexpensive home-phone service. The software costs $19.95, though you can try it free for seven days to make sure it works to your liking.
Based on my experiences, it should. I tested it with an old, expired MagicJack dongle I haven't touched in probably two or three years. (By "expired" I mean the associated account is no longer active.) After some initial hiccups, it worked like a charm.
In case you're unfamiliar with it, MagicJack is the gizmo that plugs into your PC and provides unlimited local and long-distance phone service. (There's also MagicJack for iPhone, which is pretty cool.) The newer MagicJack Plus works similarly, though it can plug into your router for PC-free calling (which is far more convenient). Whichever MJ you use, you will need a PC as part of this equation.
If you don't already own a MagicJack, you can pick up a used one on eBay for around $10 or $15. (GVJack App's developers say they can be had for "under $3," but I've yet to find one selling for anywhere near that price. If you know a good source, by all means share it in the comments.)
After installing GVJack App, I plugged in my old MagicJack, connected a phone, and picked up the handset. Dial tone! But then, when I tried to dial a number, the software didn't seem to capture all the digits I'd pressed, and the call didn't go through. This happened repeatedly until I exited the GVJack App, unplugged the MagicJack, and then restarted everything.
From there it was smooth sailing. I could make and take calls via Google Voice, and the sound quality proved excellent for incoming and outgoing calls alike.
GVJack App provides a wealth of calling features, including a priority-call table (certain numbers get a special ring), call screening, talking caller ID, automatic redial, and so on. Suffice it to say, GVJackApp is considerably more versatile than MagicJack proper. Interestingly, when you exit the software, your MagicJack goes back to its normal function (if you need it to). No permanent changes are made.
To summarize, for $20 plus the cost of a MagicJack, you can enjoy unlimited phone service at least through the end of the year. The only real downside is that, as with the original MJ itself, you need to leave a PC running 24-7. If that's a deal breaker, the Obihai OBi100 sells for as little as $43.99 and gives you the flexibility of working with services other than Google Voice.