I read this when you posted it yesterday and started to think what I could suggest. Then I realized that it's pretty presumptuous of me to suggest to anyone that they should offer a certain piece of hardware, so that left me thinking what service could be offered. An easy one would be either an offer to remix through quality outboard or master someone's material. While you wrote that, "I'd love to do a mix one but "realistic" isn't easy to achieve when it comes to judging someones mix (is it really them?), sound quality etc on the web.", I still feel that anyone with sub-quality gear would be more than happy to have someone offer their services. Okay, that leaves out the other members whose studio setups do not suffer from this inadequacy. In that case, you can always offer them a beer!