[I did most of this research in 2006. Nevertheless, I imagine my conclusions remain valid.]
Looking for a spice grinder is tough! Spice grinders are hard to find--they fit a narrow (yet general purpose) niche between coffee grinders and pepper mills. The best advice I found about choosing a spice grinder is a Cook's Illustrated article about Grinding Spices at Home. The short summary is that electric is the way to go and that the amount of heat it releases doesn't matter.
The most popular grinder seems to be one from Krups. Cook's Illustrated named it its gift ideas for 2005. Also, cooking for engineers endorsed it. Presumably he endorsed it because he got it due to the Cook's Illustrated review.
Since I only had one independent review endorsing Krups, I decided to do further research via Amazon. I looked up many brands and read many reviews. Here are my notes:
- Krups - some models (203-42 & 203-70) are hard to clean. Other models (gx41000) may have an issue with static electricity, but that might not really be a problem.
- Kitchenaid - model bcg1000 may be messy, though might not be bad.
- Cuisinart - model DCG-12bc isn't a good grinder; it grinds neither to a consistent granularity nor grinds finely.
- Delonghi - model (dcg39) died quickly.
- Braun - models ksm2 and kmm30 seem fine.
- Hamilton Beacn (sold at walmart) - some products have good reviews at amazon; some don't.
- Mr Coffee (sold at target) - model ids77 seems good; some other models are hard to clean.
I plan to go to Bed, Bath, and Beyond and pick whichever model they have of these three brands of grinders look good.
Result: I ended up buying a Krups Fast Touch Coffee and Spice Grinder. It seems to work reasonably enough, grinding fairly small quantities like a dozen peppercorns mixed with two slices of ginger. (I made chai tea.) It's hard to "pour" out such small quantities of spices, and even if it can grind smaller quantities than that, it probably wouldn't be possible to extract the powder. Also, I seem to have the same complaint as many reviewers of many grinders: my grinder is a bit hard to clean, though I'm not worried much about bacteria because I'm just using it for spices. (The base is connected to electronics and therefore can't be rinsed; cleaning thus requires scrubbing with a damp paper towel.)
Incidentally, while researching spice grinders, I found two good reviews on a very related product: pepper mills.