I just discovered a rather unusual way to infini-stall your opponent while farming t5. Unfortunately, there's absolutely no way I can think of to actually set this up since it relies on your opponents deck, but it's very useful if you happen to get lucky with it.
My opponent (morofuze, I think? Death/poison, anyway) happened to have a nightmare on the top of his deck when I used a mindgate. I used my nightmare to give him a whole hand of creatures he couldn't play (amber nymphs, in this case). This meant he didn't draw, so the nightmare was still on top for me to mindgate again. And so on, ad infinitum. He was unable to play a single card for the rest of the match.
Obvious problems for this: Since it relies on your opponent having a nightmare on the top of his deck, you can't actually set this up, only take advantage if you happen to get lucky. Also, it wouldn't work on FG's, since they draw two cards per turn. Finally, since I happened to have an amber nymph out, I could guarantee he'd never get enough quanta to play a card; if I'd been playing a rainbow deck without that nymph, he'd have eventually been able to play some cards.
If anyone can think of a way to get around that first problem, though, I think it'd be fun to experiment with this a bit.