I have used this before, but I can’t remember the name of the site that allows one to enter the cities and approximate dates, and it shows airfares for several dates before and after the dates entered. Can someone help?
Google Flights?
https://www.google.com/flights/
Orbitz does, if you search for flights (not packages) and check the “My dates are flexible” checkbox.
You might have used Google Matrixwhich preceded Google Flights.
The Southwest website also lets you do this, showing minimum fares for an entire month. Very useful if you are flexible.
I don’t know if Travelzoo is still up but they used to have a great feature for last minute deals. The deals would come out every Tuesday (I think) for the upcoming weekend. They would list several cities with cheap fares. Great deals for someone who just wanted to get away somewhere for the weekend.
Kayak also does this.