Re: Activities for learning letters, numbers, and colors... for toddlers
I think you're doing good with what you're doing.
On thing my dd enjoyed when she couldn't get enough of learning letters was I'd open a word document on the computer and set the font fairly large and let her type letters. She'd type it and tell me what it was (but you could easily tell him too). We'd alternate between setting caps lock and leaving the letters lower case.
Books (and lots of them) were the other thing she loved. She ate up books - especially letter books. Still does actually.