Re: Official Warning
All domain name registrars take over your domains if you fail to pay. The good news is that you get a full month of grace period during which nobody can take your expired name... but if you go the entire grace period without re-registering it, then poof.
But the way the system exists now, there's really no incentive for registrars to put domains back into the public pool-- at best they'll put them on auction, and you can bid for it back. At worst, it gets permanently squatted. (Failed auctions get permanently squatted, for the most part. The might be re-listed at auction once every few years, at best.)
I started registering names with Network Solutions back in the day when they were the only game in town, and I've been too lazy to switch-- which is stupid of me, because Network Solutions is very expensive compared to pretty much everybody else. Right now I have 15 domain names, including some decently good ones. (I'm fond of webluminary.com, but alas it hasn't sold yet.)