TITLE: Good ways to organize old personal mathematical resources
QUESTION [27 upvotes]: I am wondering how the other Mathematicians organize their old mathematical resources, like calculation drafts, class and seminar notes etc. 
These old resources may be related to a wide range of areas, and if organized effectively, may be useful for future learning and research.
I myself have a huge stack of old materials, and I scanned and classified some of them lately. Not sure if there is a more efficient way......

REPLY [7 votes]: Thanks to a blog post by Tim Gowers (https://gowers.wordpress.com/2013/10/24/what-i-did-in-my-summer-holidays/), I discovered TiddlyWiki (http://tiddlywiki.com/).
So far, I've only used it to capture odd jottings, such as notes about references/information sources, ideas to try out, and so forth.  I can see that if I devoted more effort, I could make it much more effective.  In particular, the ability to tag and cross-link items in various ways is very useful.