Mango/HSBC are unfortunately closing shop, but there are still netspend and other accounts around offering ~4-5%. I think the max you can have is 3/bank, and 5 total, but since there are different providers you might be able to get around 7 total, so ~$35k@~4-5%.
http://www.fatwallet.com/forums/finance/1434408/There's also Santander, which will net you ~$20/month from holding ~$375/month on average ($750 DD from employer every pay period, which is ACH'ed out the next week) and completing 2x bill pays per month, which is a return of ~5%.
I'm going to try to do the CCU for 5+% and then get as many of the smaller 5% accounts I can. I'm not sure if I can swing it, but I might be able to get ~$50k-$60k at ~4.5+%. I'm putting enough in my 401k to stay in the 15% bracket, so fed taxes shouldn't be too bad either.