MemPad is a quick notes taking freeware with a clear winner feature than Notepad - a structured index (that's to record everything in the form of tree structure).

ShirusuPad is a free and powerful desktop sticky notes (post-it note) application, main functions includes desktop memo, to-do list, timer to remind, etc.

As the saying goes, the worst pen is better than the best memory, even if one person's memory won't be better, when things become more and more, or after a long time, some things will be forgotten more or less. Crawler Desktop Notes this compact desktop memo tool, it can help you record ordinary trivial things, in case of forgetting them.