At least in Norfolk you can have your bag inspected in your presence by TSA before it is sent into the baggage system. Don't know if this is limited to the airlines on the 'far' side of the terminal (the former arrivals/baggage area, where United, Northwest and Southwest are now located), but the drill there is check in, the ticket agent will attach the appropriate destination bag tags, you then lug your bags over to the TSA screening stations next to the checkin desk, and either leave them and go, or wait till they open/swab/etc. the bag and attach the TSA-blessed hologram sticker, and tell them to re-lock them. Once TSA is done, they'll put the bags on the conveyer belt behind the ticket counter.

You may on occasion get nasty looks from the TSA inspectors, but be sure and stand your ground (politely, of course) that you want to be there while they inspect them, and CONFIRM that they've put the locks on AND spun the dials. I never leave the area until I've verified with my own eyes that the bags are locked, have been placed on the conveyer, and have travelled out of sight.

Again, I don't know if this is limited to the UA/NW/WN side of the building, but I thought I remember seeing the bag screening stations on the other side of the building too, where US/DL/AA/etc. are.