I want to add USB to Serial (to program chip) to my custom PCB (ATMega644p) so I don't have use FTDI adapter. What would be least expensive solution? Preferably thru the hole and as little footprint as possible....
I looked at ATmega8U2 that's used by Uno boards, and was hoping there's something easier to implement out there... 
CP2102 module with DTR connected to 0.1uF cap to the reset pin.
MIKROE483 from mouser.com is one of the least expensive non-ebay solutions for an FTDI module.
Here's one on a card I made
Not bad! Thank you!