Hey Birger, thanks for a reply!
The program is too complicated to be web-based. Well, maybe porting it to Flash would help, but I'm not sure, as I know next to nothing about Flash.
I've already looked at PayPal - they offer very limited service to residents of Latvia - I could only send money, not receive it.
Sure, I could put ads on the site, but I don't think it would be much use - I imagine people would sign up, "set-and-forget" a ticker and rarely come back to the site itself.