Spellchecker + Network Effect = Better Spellchecker?

I’ve been having a few email discussions relating to whether or not it’s best to use a standard dictionary of words for an OPAC spellchecker or an index created from the actual holdings of that library…
Standard dictionary
pros: correct spelling
cons: suggestion might not find any results, might not contain buzz/new words
Custom dictionary
pros: suggestions should find results
cons: will contain mis-spellings (e.g. “mangement”), needs regular updates, might be difficult to extract the words from ILS/LMS/OPAC
I’m beginning to think that the best of both worlds might be to start with a standard dictionary and then let your users/patrons build upon that. In other words, whenever someone carries out a successful keyword search on the OPAC, automatically add the keyword(s) they used to your dictionary so that they can appear as spelling suggestions in the future.
Any comments?

HIPpie "Did you mean?" ready for testing

I’ve just finished plugging the first bit of HIPpie into our test OPAC:
hippie_spellchecker
I’m gonna be out of the office for most of next week (3 days in London at Online Information 2007), but I’ll start contacting those of you who said you’d like to be involved with the testing. The test code just requires you to paste a short block of JavaScript into one of the HIP stylesheets (searchinput.xsl).
At present, the version I’ve plugged into our test OPAC uses a generic US word list, but the idea is to allow libraries to either upload their own word lists or choose from country specific ones.
Although the code needs to be able to create links that contain the HIP profile string and the session ID, neither of these are actually passed back to the server at Huddersfield (just in case session privacy is an issue).