Skype is very useful - I don't use it as often as you do, but it's still handy to have for when I'm travelling - I take a memory stick with skype on it everywhere I go, so if the internet cafe I'm visiting doesn't have it installed I can still use it.
The calls are really cheap, and I only top up credit about twice a year, which gets me quite a few nice long international phone calls.
The quality isn't just good - it's often BETTER than a regular phone line if you have a decent headset
