I use BankDirect.

1000 miles for signup
1000 miles for being referred
5000 miles for direct deposit
1000 miles for using free online billpay
100 miles/month per $1000 of avg balance
1000 for each successful referral (up to 10)

I've netted 20k miles in 3 months off my checking account.

Additional plusses:
They reimburse ATM fees
They pay interest in addition to miles

Minus:
Pretty hefty ($2500) minimum balance to avoid fees.

Regardless, I do think they're a far better checking account option than what NetBank has on offer...

And @ 100 miles per month per $1000, their ongoing mileage offers are almost as good as the brokerage account offers (that generally post in several months and have early account closure fees).

Oh, another great thing about BankDirect is that the miles post very promptly. Actually, they send miles twice a month, so my referral points show up pretty quickly. And my average balance miles for a month closing on the 30th will show up somewhere between the 2nd and the 4th. Nice!