Free keyword research tools

Some notes on some free keyword research tools:

SEOBook is Overture/Yahoo data. See UK version direct here:
http://inventory.uk.overture.com/d/searchinventory/suggestion/
...it forces US spellings, puts singulars and plurals together and changes word orders

Keyword Discovery have a UK dbase but not sure if you can reach it for free:
http://www.keyworddiscovery.com/start.html

Overture and Wordtracker-free (US) for free together at Digital Point:
http://www.digitalpoint.com/tools/suggestion/

Wordtracker-free US:
http://freekeywords.wordtracker.com/

Google Trends shows, er, trends:
http://www.google.com/trends

More:
http://www.dwoz.com/default.asp?Pr=123

For free, I haven't seen a tool that will take a seed word and make suggestions that do not include that word (a thesaurus will do some of this though). Paid, Wordtracker does this the best, I think. Test it on trial.

Best UK dbse I've used is currently Wordtracker UK. Overture UK is very useful but it forces US spellings, puts singulars and plurals together and changes word orders.

Keyword Discovery has lots of fancy graphs and stuff.