5lines is a blog posting a new limerick every day.
There are also several new items in the Bookshelf section "On Nonsense," among them a number of hard-to-find articles by G.K. Chesterton.
Of course, the "Picture" section still has a lot of full limerick books, among them JP Benson's Woozlebeasts and the impossible-to-see-anywhere-else A Peep at the Geography of Europe (c. 1824). No need to repeat that these have been contributed by the illustrious Arthur Deex.
Finally, take a look at the "Nonsense in the Early Comics" section: it contains only strips that have never been reprinted for over 100 years!