I've published a few posts about VueScan; it's a well regarded cross-platform scan control software package that appears to be a one person show. The author's personal focus and prolonged dedication has produced an idiosyncratic product that, with a few quirks (auto-crop isn't what it could be) performs admirably well. I bought a "pro" license, so I get my updates as long as Hanrick toils away.
I've mostly used VueScan to do print and a few negative scans, but recently I worked on a set of my mother's slides. These range from about 40 to 50 years old, in various states of repair. I used Nikon CoolScan V I bought about 3-4 years ago, it's oddly still about state of the art for slide scanning (though slow now). I started out using Nikon Scan 4.02, downloading the latest OS X version from Nikon's support site (yechy non-Apple installer btw. I installed as admin, but the app works for a non-admin user). It's a quirky mix of various semi-integrated packages that Nikon resells, but it mostly worked. It was slow however, and I wasn't impressed with the results various image adjustment options. I got the best results turning everything off, working with the clumsy levels tool, and using Digital ICE for damaged slides. Performance on a G5 iMac was dog slow and, really, it was clumsy.
I then tried the same images on the G5 using the latest version of VueScan. It worked beautifully. Results were better than what I got with Nikon Scan. I didn't fuss too much with white balance or levels, I went with the very good initial results then dropped the 24bit TIFF into Aperture for finishing. From Aperture I exported high res JPEGs to store in iPhoto (note Aperture doesn't allow date editing, an incomprehensible defect). The processing was a bit slow, but the workflow was great.
Next I tried VueScan, which has full Intel support, on my dual core MacBook. Processing was 2-3x as fast.
If you're using a Nikon Cool Scan (CoolScan) with OS X, don't bother installing the ugly Nikon software. Buy VueScan (cheap at the price) and finish your TIFFs in a secondary image processing package (like iPhoto, Aperture, etc).