Thanks to this thread I created a Google spreadsheet so I can enter it on my phone with every fillup. I had the last few fillups scribbled down on paper, so my numbers for about the last month (I didn't record fuel cost):
2271.71 miles
72.96 gallons
31.136 MPG
Just a note - I got an UltraGauge for Christmas (similar to ScanGauge but half the price). It's now properly calibrated for my 1998 Accord and is pretty accurate. By observing how my driving habits impact the mileage, I've been able to increase from ~28MPG to ~32MPG (my last two fillups have been 32+).
It's a neat gadget, I recommend it to anyone like me with an older car that lacks a proper dash computer.