not to sound overly harsh, but web.py seems like a big case of NIH. each of its pieces seem like v0.1s of more established counterparts. mature web frameworks are occasionally big and ugly _because_ they work around that random safari bug from 2002 or the flash 8 player's uploader non-RFC-compliant MIME-multipart requests and all the unicode encoding and DB integration nits, etc. the plumbing looks gross because the surface area of the problem they solve is gross.
and with the big frameworks, thankfully hordes of others have banged their heads against and solved these issues; with a "lighter" framework, or one of the 4328429 me-too python web frameworks from 2001-2004 that didn't really make the cut, you're volunteering to blunder into and track down all these problems yourself over the next year or two -- probably not the best use of your time or problem solving skills.