My boys (3,5,& 7) have loved Counting by 5s & 10s since we found them on a site last spring. Finally, I went ahead and bought the album. It doesn't disappoint! ITA w/ the other reviewer that these should go up to 100 or the 12s for all numbers, but I still give it 5 stars because it's so useful and catchy for kids. My kids are young but are memorizing basic skip counting (2s, 5s, 10s) and will learn the other numbers as a jump start for multiplication.
edit: the songs do go higher than 5x but you have to wait until the songs are about halfway finished.
The songs are very basic rap-inspired. No complicated melodies, but solid rhythms that will hopefully get them memorizing w/o working too hard at it.