Here are the manipulatives I didn't remember when I wrote Manipulatives 101.
"A Hundred Number Chart" is absolutely indispensible. I send my kids to the wall to walk their fingers from one number to another. Ours is color shaded- all the 5's are pale green, all the 10's are pale blue, and the rest are yellow. Great for showing patterns. There is a 8 1/2 by 11 inch number chart in the back of each "Morning Meeting" book that comes with the Saxon homeschool packages. I have another one in a plastic sleeve that we use at the table. What I want but don't need are 3x3 post-it style 100 number charts!
These are some inexpensive dice to toss around instead of flashcards. You have to have tricks like this up your sleeve-
"No, Mom, I don't waaa-na do flashcard! Please!"
"Ok, then I guess we can throw dice instead..."
"Can we? Oh, Thank you Mom! You're the best!"
These are some counting discs that I inherited from my MIL last year. We haven't used them alot for math, but they're in all the catalogs, so some people must love them. We do use them for bingo as chips. Great for rattles: old play-doh can + discs = baby busy for 5 minutes.