I take Gotu Kola extract (12:1 extract, standardized to 16% triterpenes to be exact). It doesn't contain caffeine but acts like a stimulant. This may sound strange but although it is a stimulant I feel very relaxed and focused. The effects are felt within 15 minutes and lasts about 3-4 hours. I normally take it in the morning and is helping me overcome my addiction to coffee.
I use Gotu Kola for social anxiety and has worked wonders. It really is a diamond in the rough....I wish NP would go ahead and start selling a real good extract of this stuff.