Here's what I'd like to see it do at a minimum:
1) Handle Nikon D70 NEF, including the fact that Nikon NEFs store the ISO in a non-standard place
2) Keep all the downloading features currently available for JPEGs
3) Display NEF (understanding that it will be slower than JPEG) including thumbnails
4) Handle renaming from EXIF info just like JPEGs
Like to haves:
1) Convert to ... (JPEG being most important)
You'll never be able to handle RAW editing as well as Photoshop or Nikon Capture, so I'd suggest you don't bother trying. As long as I can get the NEFs onto my harddrive using the organization I want, which cam2pc is GREAT at, then convert them to JPEGs and enhance them for upload to my webspace I'll be happy. For web-sized pictures I don't need all the RAW options (assuming I didn't screw up the white-balance, or something like that), just a quick-and-dirty convert to JPEG using the parameters saved with the RAW file in-camera.
BTW, in case you haven't seen it, there is a free open-source RAW converter called dcraw available at
http://www.cybercom.net/~dcoffin/dcraw/. Hopefully it can help jumpstart your work.