I found this website while looking for counting and matching games for very young children. Often, what you find are games that include too much (counting up to 10 or 20, asking children to find more than 1 attribute at a time, etc.) but this website is just perfect. The games only include number sense up to 5. The graphics are clear with familiar pictures and site itself is not too busy.The first 2 games are perfect for preschoolers (Gingerbread Men and Ladybird Counting).
Check it out here.