$155 Roundtrip (non-stop) Air Tickets for LAX/SFO To/From JFK at Delta Air Lines, travel before 01/14/2009
I don't know if it works on other cities, but you can try. Some says use Orbitz, but I personally prefer Yahoo! Travel to start with the search, then book with Priceline to save the $7 booking fee at Yahoo! while earning 3% cashback at Ebates.
Step 1. Go to Yahoo! Travel to start your search. Enter your To/From cities, change connection to 0, and check the "Use Flexible Dates" option, then hit search.
Step 2. The search results should show up in the next page, where you'll see the cheapest deal on top, which is Delta Air Lines at $150 in this case. Click on "Select" to contiune.
Step 3. Here shows all the valid travel dates with this offer. Enter your desired departure date first. If your date has no seat, the system will show you another near by date that has a seat, or you can try another date. Then do the same thing with the return date. You'll have to try few combinations here to get the best result. I tried 12/31 & 1/8, which works fine; however, although 12/25 has a seat, it will end up with a connecting flight instead of the non-stop.
Step 4. Once the travel dates are set, you will see the final price comes out at USD$155.00. However, Yahoo! Travel charges a $7 service fee, which you can avoid by booking at Priceline, while earning additional 3% cashback if you go through Ebates. That's $11.65 saving, which you can put it into a better use such as a meal or transportation costs.