Shotting RAW, import into Aperture. Stack, tag, sort, discard, delete, upload any I like to Flickr. Anything I feel needs serious noise reduction, I export as a 16-bit full-size TIFF, load into NoiseNinja, de-noise, then import back in as a new master version.
For printing, I have ICS/ICC profiles for any print service I use, generally either the Costco one-hour printing (if I'm in a rush) or Mpix (if I'm willing to wait). So I'll create additional versions if I'm getting prints, and make sure the color's right for the service using on-screen proofing (and crop down to a different ratio if I have to).
I also have a smart album in Aperture automatically created from anything I've uploaded to Flickr (it's easy, since the FlickrExport plugin Fraser wrote stamps a 'Flickr ID' metadata value into any uploaded image, so I just made a smart album called "Flickr'd" which is any image with a 'Flickr ID' metadata value), which makes it reasonably easy to manage my Flickr photos from in Aperture.
For whatever it's worth, I'm running Aperture on a MacBook Pro with max'd out RAM, and an external 160GB Firewire drive for my Aperture library.
