We only have one tripod between the two of us, and I'm not that comfortable with the tripod Justin mentioned (the model we own). It's a terrific, high quality tripod, to be sure, but it weighs a ton and it always leaves me frustrated during setup and stowing (adjustment once it's upright and secured isn't quite as bad). It's pinched my fingers pretty badly before, and my arms are always sore after I've used it -- and that's just using it, carting it a quarter mile or less to take a photo, not hiking with it, which is do-able but not fun.
We are both currently lusting after a carbon fiber tripod -- LIGHTweight, strong...you guessed it, expensive. Someday, but not yet.
We shoot exclusively with Canon gear, and our two best lenses are "IS" -- image stabilized. While the lenses each cost about the same as a pro tripod, they have the advantage of letting us shoot HANDHELD shots at very low shutter speeds. And don't even get me started on aerial photography and how useful the stabilization is there (though it doesn't do a bit of good when we encounter turbulence -- we need a "flight stabilized" aircraft, for that!)
If I don't have a tripod I'm comfortable with and can count on not to dump my lens and camera body into the muck, I'd rather just miss some shots... and that's what I do. That said, even on trips Justin's taken on his own, I can usually pick out which ones he shot with a tripod versus hand-holdingan image stabilized lens.