I'd say that my memory is fairly good for the most part, although I do tend to make little post-it notes to remind myself about pretty important stuff from time to time.

Although I currently keep a list of on-going/eventual art projects that I'm either working on or would like to eventually tackle. Lately the more large-scale projects take me several months or more to finally get around to, so keeping a note of a cool scene is super handy. I'd kick myself if I had a killer idea that I'd like to draw and later forgot about it because I didn't write it down! ;^;