I've been keeping track of words which return a link to a dictionary definition of the word in Google. Dictionary words are those that are written but not written about, haven't been subject to the corporate/band/blog word grab, or aren't otherwise popular words.
germane
paucity
reticent
cantankerous
suppositious
abstruse
whinge
assiduous
surreptitious
proclivity
disparaging
sporadically
hypertrophied
pallor
acerbic
surfeit
Many of the Dictionary.com Words of the Day are probably dictionary words as well.