Steve Hall, the founder of the must-read advertising industry blog Adrants suggests these blogs about copywriting and ad creativity:
Writing that catchy slogan getting you down? Can't conjure the name of the doohickey your client's marketing? Will the following sites help? Well, not really, but they're fun to check out:
The Advertising Slogan Generator
Random Surrealism Generator
Which ads zing, which ones tank? These industry insiders blog on creativity in advertising, and much more.
Chimp Media Monitoring