I posted a lot of good articles here:
http://www.bodybuilding.net/suppleme...ed-it-549.html
I personally don't believe they're worth it. According to science, aside from citrulline malate, akg and the like aren't worth it. Make sure to really read the link I provided above so you can make an informed decision.
However, I recommend supplementing something like citrulline malate. It's relatively cheap and helps you get that last rep.