NO-releasing supplements don't seem to work for everyone. I suppose that means that some people's bodies already make all the NO that they can use. But I tried a free sample of BSN's NO-xplode and got amazing results!
I've always been extremely skeptical of supplements, though I've tried a few. (My favorite instructions: Take two tablets, then put extra effort into your workout!)
Anyway, within an hour of taking this stuff, (and working out, of course) my arms and abs were pumped up like never before. And they stay that way, all day. I rushed out and bought a jar.
Next question: Does it just puff you up, or does it lead to real strength improvements? After a month, I say "yes." I've been moving up the weights every week (I was kinda stuck, before) and I now seem to have extra stability in the big lifts. Now we'll see what happens when the cycle is over with.
Cautions: I had some trouble sleeping at first. I was laying in bed, wired, and feeling my pulse in my whole body. Either that subsided, or I got used to it. I was a bit worried about blood pressure effects,and checked it for a few days. It was a bit high in the middle of the day, but normal in the mornings.
Shop carefully if you buy any of these products though. The prices on the web vary by as much as 100%. Probably, you can buy the active ingredients separately and mix them yourself for a bit less money.