am using a national geographic 2345 shoulder bag, it comes with a so called tripod velcro strap at the side, am able to hook my tripod onto it, u may wana check it out if ur lookin for a small shoulder bag..
I think a lot of the shoulder bags (esp bigger ones) have them, or can be fitted with tripod straps. My Tamrac Pro 8 came with them.
I prefer not to use them though -- don't like the feel of the tripod wobbling around under the bag. I'd rather use a separate strap for the tripod, or carry the tripod free, resting it on the top of my bag as I walk, with my forearm on it.
Vanguard Oregon 27 fits the bill, IMHO. Keep in mind that putting all that weight on one shoulder is bad for your posture. Had one once but decided to sell it because my friends noticed my shoulder became higher than the other. My set-up isn't even considered heavy back then. That was two years ago and until now I stand funny. Just a heads up.