This is a simple issue (more of a suggestion, really), but I feel like things such as Direct State Access (EXT_direct_state_access) should come as part of one of the packs of extensions. I know it's not exactly core (the name still has EXT all over it and such), but it's been begged for and asked for by many individuals in the community since OpenGL 3.0 (http://www.g-truc.net/post-0279.html, http://www.youtube.com/watch?v=btNVfUygvio&t=26m00s).
I don't know if there's a "Common Extension" file that maybe it belongs in, but I would like to see it added if that's possible.
If you'd like me to collect a bunch of EXT-functions that would be useful to have in general and make a pull request for it to be in
stdext, I can do that too. Just let me know!