Palm has some things on sale on their website, including this dictionary - thesaurus for $9.95 after a rebate:

Ten years ago if I had seen something like this, I would have thought it was really cool (and it probably would have been a lot more money). But in this day and age, is something like this more trouble than it's worth? Even if I was a prolific writer, I'm not so sure:

• Most writers will have a laptop or desktop computer
• Most people with computers are connected to the Internet and can access dictionary.com or thesaurus.com, two of my favorite language sites
• Most computers have a built-in thesaurus
• It makes more sense to use available tools on the computer (assuming one is writing on a computer) where, for instance, one can leverage the clipboard, than to switch to a handheld device

I suppose if you do your writing on the Palm (or other handheld), then yes, it is a good place to have a lookup tool. But as much as I like my TX, Graffiti is a poor substitute for a good keyboard (I still haven't gotten used to Graffiti 2).