[amenghra]

For code: create a readme (for your future self) that documents the state of things and dump the whole folder/project on github.

Often times, you'll have a hard time running old stuff you wrote (finding the same versions of the compiler/libraries/tools/etc.) so try to vendor your dependencies if that's an option. Even if you can't run your code down there road, having the source file can be a fun read or useful.

For non-code stuff: convert to a plain file, PDF or screenshot and file it away in your Dropbox/Google drive/whatever.