If you are really interested in volunteering your seat for a bump, get to DFW early and ask about volunteering when you check-in. We did this last year for our flight to CDG from DFW and the agent called and had us put on the volunteer list. Our seats were needed and we received $800 each plus hotel and food vouchers. All other flights were sold-out so our only option was to try to fly out the next day. We were allowed to change our return flight so that we could come home a day later than originally planned. We also asked the wonderful gate agent (AA received a letter about how great she was at managing people) to put us on the volunteer list for the next day. The next day our flight was again oversold and we were the first ones on the volunteer list. We were bumped again and recieved another $800 plus hotel and meal vouchers.

Good luck!