Shoot, it doesn't even cost that much.

I would have to say that I do not regret shots that I have taken no matter how lame but I do regret not taking shots.  I rarely discard a shot.  For the versatility it gives me I shoot in RAW.  I have since I bought my first digital camera – a Canon 10D.  I can remember the voices saying you have so many files that you will never use and the files are so large you will run out of room on your hard drive.  I would laugh at these comments.  Hard drives keep coming down in cost and at a rate faster that my ability to fill one.  Also I still remember when I bought my first hard drive (yes there was a time that you used floppy disks to run your programs and store your data).  In was a 20 Mbyte hard drive for my IBM XT and it cost me $200.  I can remember thinking I would never fill that up.  My only fear is a hard drive crash.  I have had a few.  I routinely back up my files to a second hard drive and about once a year copy all the files onto a third hard drive.  But the hard drive cost is minor compared to all the other costs associated with photography.