Just a couple of ideas on the fly this morning--
There are other Anno books, too (Anno's Magic Seeds, and The Mysterious Multiplying Jar--or something like that). A couple of favourites here have been Malba Tahan's "The Man who Counted" and Denise Schmandt-Besserat's "The History of Counting" (as well as the good old Number Devil, of course!)
Really good, but unfortunately out of print, are the Young Math series published by Thomas Y. Crowell in the '60s and '70s--simple presentation of some very sophisticated concepts. Our public library has a pretty good selection of these, but I do wish some reprint publisher would snap up the rights to those and re-release them.
Also terrific and out of print are Catherine Sheldrick Ross's geometry series (Squares, Circles, Triangles). I bug the publisher about once a year to reprint those, but haven't had any luck so far!
You could look at Julie Brennan's Living Math website; she has a fantastic list of books about math, sorted by grade and subject.
www.livingmath.net peace
minnie
ETA: Theoni Pappas's books are excellent, too! (Penrose the Mathematical Cat, etc.)
