While wandering sites, looking for information on Crookshanks, I found this most interesting post.
I recently bought a copy of The Mummy: Unwrap the ancient secrets of mummies tombs by Joyce Tyldesley. This book is basically a coffee-table type book that relates the history of the mummy and the world's fascination with them. As mummies became popular in Europe (specifically England), several individuals held public mummy unwrappings. In 1821, one Joseph Pettigrew, a London surgeon, held the first of several public mummy unwrapping exhibitions. Pettigrew kept excellent notes of his unwrappings, and eventually published History of Egyptian Mummies in 1834. Very coincidental that Rowling would choose the name Pettigrew (which has no other apparent significance) for the man who reanimated Voldemort.
By now, you're probably thinking that I've totally lost it and that this tenuous connection is, at best, coincidental. This connection, however, becomes much less coincidental when you consider that Pettigrew's book was illustrated by one George Cruikshank. I would like to add that both Rowling's Pettigrew and Crookshanks the cat first appeared in Prisoner of Azkaban after Ron's trip to Egypt. Still think it's a coincidence?
I think it's fairly safe to assume that Rowling must have heard of Pettigrew's book (if she hadn't read it in her research), and selected the names from it. While this probably means nothing, it may be an indicator that future novels will start to implement aspects of Egyptian magic. So the next time someone claims that Crookshanks is so-name because of his tail, you can annoyingly correct them and explain that he is named for the illustrator of a book on mummies.
The funny thing is, in my post about the Crookshanks art, I had a sentence which I deleted out. 'What kind of name is Crookshanks, anyway?'.
I think the writer of that post probably had it right ("it probably means nothing") but it is interesting and I'd believe that that's where the names come from.