I have an old, heavy Slik tripod I use occasionally, but I hate lugging a tripod around. I do appreciate how invaluable one can be at times, but I make do with two alternatives. First is a TekPod XL monopod. It is not cheap...around $400 a while back. It has three short legs that can convert it to a tripod of sorts, but these will not be adequate in situations like wind. It is light, carries in a bag with shoulder strap and fits in my moderately sized suitcase. It will not match the possibilities of a full tripod, but with some care and practice can yield nice results.
The second alternative is cheap and invaluable. I made my own bean bag of sorts. Rather than use rice, which is often suggested but is heavy, look for something like a travel pillow and put the "stuffing" in a zip lock bag. I keep one in my car and get great results using it on the window sill or any other solid object.