What state are you in? A lot of credit unions require you or an immediate family member to reside in the state where they operate. Try shopping around the different credit unions and banks in your state and see what you can find.
My wife and I currently get 2% interest on the first $10,000 in our checking accounts at our credit union in Washington state, with the requirement that we each make 12 debit card transactions per month and get online statements. We use it for our liquid cash/emergency fund. For us the interest rate is good enough to make sure that we make enough small purchases with the debit card each month. Perhaps you can find something similar in your state.
Another credit union in our state offers 4.07% on the first $500 in a checking and a savings account. We keep $2,000 there (2 checking, 2 savings) at all times as part of our emergency fund.
As far as nationally available opportunities, maybe some other people can chime in. I wouldn't mind finding some higher yield as we increase the size of our emergency fund.