There are 4 of those!

2 are from Amex (the bank), so the above applies to them also.

One is the Citi HH Reserve, for which there's little information about churning ability to date. It gives you 2 free weekend night certs that expire in a year, plus Gold status, but no bonus points.

This other one from Citi:

http://www.flyertalk.com/forum/credi...nors-visa.html

is one of the most frequently-churnable points/miles-earning cards out there. Start by reading that thread's Wikipost.