OS Level Proxy setting
 

The question is how do you get around proxy inposted by ISP on port 80 designed to keep you from running you own
web server? Or is there a defaultproxy like default gateway
type of thingie?

There really isn't, unless you can get somewhere else to run forwarding to you that will forward on a non-standard port, or of course you could run an ssh tunnel, but this is all dependant on having an un-encumbered server outside the ISP's firewall.

Honestly, if they block something as inocuous as 80, but leave something as potentially volatile as 25 open, then I would call them up and cancel telling them that they're a bunch of cheap bastards.

Cheers,

Finegan