As a by-product of a larger web project we're working on, we ended up doing a fair amount of database and coding work on English dictionary / definitions / synonyms / thesaurus recently.
Thinking about this in retrospect leads me to believe that if spell-checker, word definition lookup and synonym lookup functionalities are made available in the form of web APIs, these could be useful to (many) developers. (I'm not really sure if such APIs are already available.)
One mass-use application that I can think of is to spell-check/correct user generated/submitted content.
What do you think? Do you think this is something you and/or others will find useful? If so, in what ways?
If we find enough interest (>20/25 ayes?) here, we'll develop and publish these (free) APIs in the next couple of weeks or so and announce the availability here.
What do HNers think?