I would like to have my 4th grader work on some sample problems for math competitions for elementary school.
I bought Math Olympiad problems for elementary and middle schools- some are good and some are just too hard (including for me!). Are there any books that target just elementary school?

http://www.artofproblemsolving.com/...ementary_school_mathematics_competitions

http://www.onlinemathleague.com/
(the aops link to oml was broken)

Look! Free online discussions for elementary math Olympiads!
http://www.artofproblemsolving.com/Wiki/index.php/Math_Jams
(that's only for the middle school though)
I hope someone else answers who really knows so I can find out too.
You already know about Life of Fred & Beast Academy & art of problem solving & khan academy & YouTube has lectures on everything.

Check out this video on YouTube:



Ok.  I have not watched this.  I have no reason to watch it because my kid's still learning simple arithmatic but it's a full length lecture 1:30 m about moems problems.  There always seems to be something on YouTube.