My DD - aged 7 months - seems to enjoy rhyming books as well, so I have been searching the library high and low to find new ones. In addition to the ones already listed, I recommend
Noisy Poems - collected by Jill Bennett (very fun and suitable for even young babies)
Chanting Rhymes - by John Foster and Carol Thompson (in fact, any book with John Foster's name attached is pretty good)
Bear Snores On - Karma Wilson. Very basic story, told in rhyme, would be lovely for a toddler.
Boom, Baby, Boom, Boom - Margaret Mahy - a book where children can join in with the sounds that Mummy makes as she bashes her drums
The Wobble Bear series by Ian Whybrow - I love these
It's Heaven Having You - Giles Andreae - a lovely book, with a very touching rhyme.
Hope this helps, let us know which ones you try out and what your DS makes of them