Limericks, like haiku, are a particular kind of verse. Although a few instances of verse in limerick form have appeared for centuries, it is only recently that the form has been recognized. Despite this, the history of limericks is very poorly documented -- nobody even seems to know how or where the name "limericks" originated.
There are a number of Web sites which discuss all this in detail. Maybe a good place to start is with Pentatette's home page. Like most limerick sites, there are plenty of links there to other sites. (But they're not all up to date! jjm '07Dec02)
There is now one HUGE limerick archive on the web -- and it is right here! It is the Jim McWilliam Limeric Collection. At almost 96,000 limericks I believe it is the world's largest collection.
At one time there were plenty of good limerick archives on the web, but many of them were shut down because they contained a few verses which some companies felt were disparaging to them or their brand names. The company lawyers threatened lawsuits. (It so happens that none of my verse has fallen into this category. Now, should I come up with anything derogatory, I will be careful to deliberately slam known faults in companies and products, thereby exercising my first amendment rights. And I won't be slow to poke fun at lawyers, either.)
Probably the best remaining archive after that debacle was kept by Tony Davie of the software architecture group in the School of Computer Science at St Andrews University in Fife, Scotland. Sadly, Tonie succumbed to leukemia 28 January 2003. Archie, one of the most active limricists until recently, is currently hosting that archive here, and he has a pretty impressive collection in his own right. Unfortunately, the links and some of the other stuff there are now out of date too.
There also used to be a number of author's collections, of which Cybergeezer's was my favorite. Sadly, "Cybergeezer" has also passed away. I can no longer find Mark Wainwright's site, either. Mike Mesterton-Gibbons' site is still up but last I looked hadn't been updated for a couple of years, so many of the links are dead.
All these author's sites were notable for the fact that they were CLEAN. Also noteworthy were the impressive intellectual and academic credentials of these same people. Compare these academic credentials to mine (none). Note the next paragraph. I think there is some sort of a connection to be made here, but I don't think I want to make it :-)
For those with strong stomachs, here is my own collection of filthy classics.
And then there is Tiddy Ogg. I don't know what to say about Tiddy (you'll just have to go look for yourself) but Mr Ogg should get a Pollutzer Prize for his site -- and that is meant as a sincere compliment.
Azul used to maintain a web page in connection with alt.arts.limericks, but I can't find it just now. I used to maintain a page for alt.jokes.limericks here but I'm sorry to say I have not kept it up -- and here is part of the reason.