If you’re like me you constantly have trouble coming up with words for things like… I’d give you an example but I can’t think of the word. Luckily there is now a Reverse Dictionary. You type in the definition of what you are thinking of and it gives you a word. Link
http://en.wikipedia.org/wiki/Lethologica
Yes, I get my fair share of bouts of lethologica, but I can always recall that word every time I've got a certain word that's on the tip of my tongue!