ATM locations, mostly. Chase has an ATM on every street corner in NYC (OK, an exaggeration, but only just). I know plenty of credit unions refund a certain number of ATM fees, but you can't do thinks like check deposits at them any more.
I don't guarantee anything but you might be surprised. In fact if you already belong to a credit union you might be very surprised. Check for the logo on your card. I belong to a credit union tied to a university that I've since moved about 2 hours away from, and except for loans (which I do so infrequently I don't mind driving for that, there's a full branch about an hour away) I've got plenty of ATM coverage everywhere I go.
I have a credit union account (First Tech CU), and I regularly deposit checks at a different CU's ATM (BECU has fancy ATMs that scan checks, so I prefer them).
In fact, any CO-OP Network ATM works just as well as my own CU's ATM (no fees, deposits, etc). They have locations nationwide, as most credit unions are members.
Edit: also included in that list: most ATMs at 7-Eleven.
Some banks and credit unions are adding "online checking depositing": you upload a photo of the check to their website. They OCR the photo and process the check. No signature endorsement necessary.
Also, a good way to avoid ATM fees is to get "cash back" when using a debit card at the grocery store.
Might not be the case anymore, but I remember hearing in the late 90's that some banks would charge you fees for getting "cash back" with your debit card at a merchant. This is probably bank-dependent though.
There's nothing special about getting "cash back" from a grocery store, there aren't any special fees associated with it. You're just buying cash from the store, it would be no different than if it had a stack of individually barcoded $20 bills on the shelf that they charged $20 each for.
