Linysys (Cisco) WRT54GL (you want the model with the "L" on the end - other similarly named router models are NOT the same, nowhere near the same).
http://www.newegg.com/Product/Product.aspx?Item=N82E16833124190$52 (they don't show you the price until you put it into your cart).
Excellent router as it comes. Double-excellent if you load third-party firmware on it (DD-WRT, Tomato, etc.)
There's a reason it comes with over 2300 customer reviews and has a five star rating at NewEgg!
AWESOME Router. I've had one for years, set my parents up with one, etc it's pretty much the most common / best basic home router out there.
I've retired my WRT54GL to backup as I've replaced it with a Cradlepoint Router. It's made for hooking in broadband air cards as well as normal WAN connections... Is wireless, and even has a battery / 12v adapter for it to use when traveling in the RV. Pretty much #1 for it's purpose, but OMG it's pricey compared to basic routers. So far it's worked AWESOME, and I can't complain.