Back on the topic (!) --
If Ambien isn't putting you to sleep, you really need to go back to your doctor. Ambien and the other prescription sleep aids are in a totally different category than the stuff like ZMA, valerian, 5-HTP, kava, melatonin, etc. Unless you have experienced severe insomnia, you won't understand, but everything I've tried that is over-the-counter doesn't even touch the problem. Not mentioned yet are the OTC antihistamines, such as Benadryl (aka diphenhydramine HCL), which are marketed as sleep aids. I'd say these are the best of the OTC's.
I have much better luck with Lunesta than Ambien. Also, Lunesta has some studies showing long-term safety and lack of habituation. Ambien has a poor reputation in this regard; in fact, there are clinics that specialize in treating Ambien addiction.
There are other drugs that are sometimes prescribed for longterm insomnia. Two that come to mind are Clonidine and Trazodone. There are also some antidepressants that can help, usually the old-school tricyclics. The newer SSRI's don't really help.
You might need a referral to a sleep clinic, which will analyze everything that could be causing insomnia, and which will have doctors who are very familiar with all the relevant pharmaceuticals.
Powerfull, Bulk Powerfull, or the bulk "1-carboxy" does actually help me to some extent. This is a confusingly labeled version of Levodopa, which is normally a prescription drug. The marketing hype behind Powerfull is pretty crazy, but it does consistently get reviewed as making users drowsy.