Finding online resources for learning Tamil rhymes is quite a task. Early introduction of Tamil rhymes can help children to learn the syllables easily and rhyme along and getting familiar with the tunes.
Here is a list of YouTube Channels that have Tamil rhymes for toddlers and kindergarteners.
Personally my favorite channel is Infobells – Tamil, their tunes are very nice with clarity in word pronunciation and background music is soothing or does not overwhelm the lyrics.
Apple Tree – Tamil has very few rhymes in it but I am hoping that they may add more songs in the channel later.
Appu Series – Tamil has other types of playlists for rhymes.