zoomkat:
, I'll almost bet it is in violation of your contract with your ISP to host a public website with a residential account.
The wording may need to be refined. The TOS more likely uses terms like "commercial website" or for "commercial purposes", Many residential accounts may run web cams, PCAnywhere, home automation servers and such, which probably are not restricted in the TOS. I know that the company I work for blocs access to servers running on ports other than the typical 80, 443, etc. I think it is due to the fact that many Trojan applications connect to servers operating on non standard ports.
This has been my experience as well. With all the self-hosted "cloud" services that have come out, most ISPs don't mind if you run your own web server for small things. They will nail you if you try to host a commercial website though.
Blocking ports doesn't really have much to do with money, ISPs make all their money from the users that pay for the lower tiers. This is to combat malicious internet use. It was common in the late 90's and early 2000's for home users to get their PCs infected with spam sending trojans or viruses. Having a few hundred users on your network max out their internet connection by sending out spam can bring a network to its knees. Blocking ports made this type of attack less profitable, and it eventually fell out of common practice.