if you're really lucky but generally no... the last time i had to buy a last minute ticket it was 800 bucks. tics for the same itinerary were usually 3-4 hundred. book as soon as you find out you have an interview.
typically when I travel, time is important i.e. I'm working until 5pm, and therefore need a 6:30 or later flight. For specific times, I'd always do best booking over 2 weeks out; less than 2 weeks is when tickets get pricey. And just over 2 weeks out, selection is limited; Ideally 2 weeks and a few days for a decent price + decent selection. I've had the best luck on orbitz, yahoo, and travelocity.
But there are services like priceline, and on united's web site (and probably other airlines) there are last minute specials. I would never rely on these if I had to get somewhere, though.