I like this idea as well. Some that have expired that I can think of are as follows:

- WN Chase VISA; 1 RT ticket + $500 Gift Cards; $5000 spend; June 2010
- SPG AMEX; 30,000 SPG pts; 10k/20k after $1000 spend; June 2010 (rec'd 40,000 for business card)
- AA Citi VISA; 100,000 AA miles; 50k/50k after $750/$10,000 spend; July 2010
- LH Barclays MC; 50,000 LH miles; 20k/30k after $2500 spend; Apr 2011

Some of the best deals for some cards are currently available and most are listed in the special credit card offers master thread.