Here is my tripod - small, light-weight, sturdy-ish, ballhead ( the ballhead is very nice to have - just one little thingy to turn and I have total control) , and able to get tall when i need it. It's a SLIK, and i use it for my RF645 and my D70. It has a varry narrow profile when closed, I can get it into my backpack easily, and it is sturdier than it looks. It's even sturdy enough for my Crown Graphic (which I no longer use because I don't have a lens for it).
Only thing is, it doesn't have a quick release plate, that i know of. But that is only an issue if you're someone that tends to click and unclick the camera from the tripod between shots. For portraiture, I use my Manfrotto for that kind of speed.
SLIK Sprint Pro GM (SBH 100)
It's tall enough that I can work with it without ducking down.