I used to use one of these to serve as a wireless receiver for a machine that only had an ethernet port.
TP-LINK-TL-WR702N-Wireless-Repeater
In addition to serving as a "wireless card" for my device it also could have been configured to serve as an access point, a repeater and a few other functions. Once I got it configured it worked well and never gave me any problems.
Edit:
I should add that to configure this I didn't have to do anything fancy, the device came with a small disc that contained some configuration software, I had to install the software and plug it into my computer to do the initial setup which wasn't any different than logging into your router normally would be.
Additionally there is more than one model that has this form factor (the nano size), it would behoove you to make sure the one you are looking at will be able to handle the sort of traffic you plan to run through it.