I use WingIDE - the commercial version (the offer they made at
PyCon2008 was too good, and the demo was generous).
It couldn't be simpler w/ WingiDE --> you set project to the top of
web2py, and set web2py.py as the default debug starting point... New
files just get discovered (I included all files recursively for "the
project", and WingIDE seems to do this dynamically - very, very
handy).
I've used Komodo (for perl, other work) .... for Python-centric work I
prefer WingIDE. The guys are about as responsive as Massimo.
They have a free version that does debugging - but I'd try a trial of
the other versions (they say 30 day trial - but it's doled out in 2
week chunks, and as I recall they give you 3...). Another thing -
even though it's "commercial" once you buy, they give you access to
full source.
Check it out - see if you like it as much as I do:
www.wingide.com
Cheers,
Yarko