My solution for this was to purchase Lightroom.

My reasoning:

• Lightroom's workflow is an awesome solution for this problem.
• It's not too expensive (certainly not cheap either though).
• It's a one time cost that saves be a lot of time.

Details...

• Lightroom allows you to run through and flag your images (Yes/No/Unflagged) using keyboard shortcuts, so I take one pass through them and just flag them all, spending no more than 2-3 seconds per image.
• I then filter them down to only the ones flagged "yes", and take a second pass through, spending maybe 10-15 seconds each and rate them using the 1-5 star range (I rarely set higher than 3 at this point though)
• I then filter down using the ratings until I have < 20 or so images that I spend some time editing.
• After I've finished I delete all the ones flagged "no"

This process works extremely well with Lightroom, but would also would work with any program that allows for fast rating/tagging.