Whenever I log on to my ISP's server a unix hint pops up. This one is great.
If you forget how to spell a word, type look followed by the portion you know.
for instance I want to know how to spell indistinguishableness, I type in
look indisting and the result:

indistinguishability
indistinguishable
indistinguishableness
indistinguishably
indistinguished