I would recommend against that. You're going to piss off your ISP, and your latency is going to be through the roof.

Go with a VPS. If you can't afford $20 a month, you probably don't have time to run a web server since you should be looking for a better job instead. Oh and avoid Slicehost. They were going downhill before Rackspace bought them out, and they've gone retarded since the acquisition. VPS.net, prgmr.com and linode.com are much better providers.