Here's a favorite, seriously. It's aimed at the "prepper community" (isn't that that we're about, though in a different meaning than the usual?). But it is stuffed with tips, tricks, hints, ways to get by on less, ways to make something out of nothing (or out of something else that doesn't work any more)....there's new material every day. The name of the site says it all:

http://knowledgeweighsnothing.com/

Remember, what's between your ears is ultimately what will get you to the Gulch.

Hey Thanks DaveM49 ,that prep site is awesome
and I've been looking for that type of battery charger.It's headed my way from Amazon.Hey I'm a Dave too.

Brain-food Bonanza!

lol.

these are interesting. I'm going to definitely check out the speed reading one. thanks.

Very cool.

Lumosity looks to be the highest-profile puzzle site, not free but very good. May I now self-servingly mention the best-kept secret but totally excellent puzzle site, http://www.gamepuzzles.com -- "Gamepuzzles for the joy of thinking". Mind candy, math as art, epistemological paradigms. Designed and made by an Objectivist. See for yourself.