1 = something that's 99% certain to be deleted when I finish reviewing (I delete any unusable ones immediately)
3 = stuff I'll not use but keep because it might be useful for compositing or for articles/guides
4 = multi-exposure images for HDR, which are re-rated 3 when I'm finished
5 = keepers
Of the keepers, I then go through, process and store all the PSDs and export the JPG for flickr/online.
I think I'll be adding a keywording step - right now I only do that if I need an image in LR for one of the few tools it does better than photoshop (auto-perspective correct, quick gradients) otherwise it's all in photoshop. While I still think I'll be using photoshop for the bulk of my processing (I prefer to have fewer, better images than the bulk editing LR favours)
I've started managing all the images I take for gear reviews in photoshop using collections and keywords, as well as a photo essay I'm working on. I think you're right about working backwards slowly though, I tried doing just for the ones on my hard drive (the last year) and rapidly got bored

One problem is that all the images I have on my network storage are uncatalogued, sadly it takes far too long to pull 1TB of images into Lightroom
