A little beanbag is the man for that stuff. Try lugging a tripod around for a day or two. There is almost always a spot that you can set up a bean bag to rest the camera on.
And if there isn't.. you'll just end up with an artsy unusual angle.
I prefer it even to those mini tripods you can get now, its more flexible, you can drape it over a branch or railings or whatever. You can just make one even, use fine seeds like flax.