This was compiled on a pretty random basis, to build a list of commonly used words to learn to spell. All the words in the sources listed below were ordered, and then counted. I pooled some (past tenses, plurals etc), some manually, some automatically. The final list here contains all the words in the final list occuring more than twice.
This was compiled from 310,000 words from large chunks of:
Alice in Wonderland, Peter Pan, 'The gift of the Magi', Alladin, and War of the Worlds, all collected from University of Minnisota electronic books archive and University of Calgary Childrens' Literature site
The 1996 parliamentary budget speach, from The Guardian's web page
65 entries from the Grollier Multimedia Encyclopedia (everything with 'art' or 'computer' in it)
Some random news items from New Scientist's Planet Science web site
'Sailing' from rrnet's web site
'Time Tag' from the Spectrum on-line magazine (this seems to have been taken off-line now)
and my own Biotechnology from A to Z