Okay, so my memory is probably better than the average person as far as being able to recall things manually. My internal alarm clock and internal todo list is HORRIBLE. So to complement that (the todo list), I'm trying to embrace GTD, by David Allen and I'm a premium paying member of Remember the Milk. That's working out well, except for the fact that I'm pretty bad about the weekly cleanup of my tasklist. I think this habit is definitely a keeper and I will be able to refine it with time. For my job, I use this ToDoList.
Now, to address my normal memory. Remembering all the details of something, like researching a big purchase, is impossible. So for that I am trying out Evernote. So far it seems like it a keeper. Its still in beta, but its ability to sync between computers combined with its ability to capture things WELL from almost any source (computer clipboard, cell phone picture message that gets OCRed, etc) is awesome! I'll keep you posted on how it goes as it progresses. FYI, if you need an invite to the beta, post in the comments here and I'll get one to you.