I seem to be having some improvement in cognition & working memory with bacopa monnieri. It's inexpensive and there's a fair amount of research on it, considering it's a supplement. I do cognitive training games a few days a week and the scores have improved noticeably. I've also been finding myself doing my work lately (programming, analysis of neuroimaging data). The interesting part is that I can still crash the next day from doing too much mental work, only the crash doesn't affect my cognition nearly as much. So, it's a bit of a double edged sword.