Can somebody tell me the actual dimensions of Lego blocks?

In particular, is there a block that is about 1"x1"? How many positioning pegs would it have?

Or, can anybody come up with a suggestion for where I could obtain several thousand stackable, interlocking blocks about 1" x 1", preferably with the body of the block about 1/2" tall. If they came in multiple colors that would be good, too.

How's that for off-topic!

tanstaafl.