Update 9/22/07: CD rates have gone down. Please check bank's website for latest rates.
New Frontier Bank has some nice rates on its certificates of deposit. The best is an 18-month CD with a yield of 5.70% APY. The 12-month CD has a yield of 5.60% APY. The minimum deposit is $1,000. These also have an Add-On feature that allows additional deposits of at least $1K to be made during the term. The maximum that can be added is $100K per term. The 12-month CD also has a step-up feature with a minimum deposit of $25K. This gives you the option to bump up the rate to the current rate being offered up to two times during the term.
Only in-state funds are accepted. Branches are located in the Colorado cities of Greeley, Windsor and Longmont which are located north of Denver. The bank has been FDIC insured since 1998 (FDIC Certificate # 34881).