I had this same frustration and same implementation idea -- proxy is awesome because any client can easily gain features by a checkbox pref "Use proxlet".

I never pursued it because I wasn't sure how I could sustain it -- I asked my heavy-twitter friends about it. They all agreed it sounded like a good idea, but none of them thought they'd be willing to pay for it.

Have you done any market research, or are you just doing it for fun for now?

Anyway, I'm happy to see it. Where's the paypal donate button?