Just saw this in FT
UA has a very nice $48 round-trip base fare from DFW-ORD and vice versa. It works out to $69.40 all-in. Sample DFW-ORD on united.com:
Saturday, March 26 UA #7594
Sunday, March 27 UA #7575
Base fare $48.00
Taxes $21.40
Total $69.40
L class fare.
Saturday-night stay required.
Travel March 4 through May 25, 2011.
Book with expedia.com and add a hotel night and you can automatically take 70 (~$96) off the total package price. Pretty nice.
*I checked and it would work with a friday or thursday evening flight