Smashing Magazine has posted some very interesting articles lately (in the last year or so, I mean). Here's one about font choice. So it's a little surprising to find them posting a relatively dangerous article, that might end up costing you time, and maybe money, if you follow the advice in it.
The "innovative" techniques that they suggest mostly have one problem in common: they're not obvious.
If there's one place where you want to be dead-simple can't-possibly-fail-obvious, it's the signup and login forms. Every little bit of weirdness, every unique, "different" way to do things, can trip users up. And that will cost you conversions, support queries, and eventually money.
The order of priority for signup and login forms needs to be: clear, predictable, simple, in that order. If it's a payment form, add "trustworthy" at the beginning of the list.
Only innovate signup and login form concepts with a lot of A/B testing.