I just want to let you know that what you're doing is awesome and I've been following it since the beginning. Browserling, from one dev to another, is a terrific implementation, and to speak to its benefits, I have used it a bunch of times because it is faster than booting up a VM for quick smoke tests. Everything has worked really well and I recommend it to everyone that mentions browser testing.
I'd love to give you money - and it sounds like you'll be offering a prepaid plan - so I'll do that as soon as it's released. If there's a mailing list please add me to it, email in profile.