Thesausus + Spellcheck

What is the primer problem of Ajex Applications that copy established desktop programms?
If the are a mere copy their is no reason for the user to change to the Ajex Application.

What are the advantages that an Ajex Application has over a desktop application?
1. You can use the program with all the data it contains at each computer that has an online access.
2. User can collaborate a lot better.
3. You can update the program very fast.
4. It can use external databases

I think that uses 2,3 and 4 you could build a thesaurus feature that provides far more value than any desktop solution.

The feature would work the following way. If Alice wants an alternative for a single word or a phrase (any number of words), the computer would check a database and provide a dropdown menu, with say five alternatives and a eleventh option "none of the above".

If Alice changes the word to one alternative the database remembers this and gives the next person, say Bob who ask the thesaurus for alternatives for the same word or phrase the alternative that Alice chose as first alternative in the dropdown menu. Over time the thesaurus feature would learn and give people the alternatives they want.
This approach could be further improved be considering the surrounding with when searching for similar cases in the history of the feature.

What are the advantages to desktop based thesaurus?
1. A much bigger database can be used.
2. You can fill that database with meaningful information. Like Wikipedia it would be a user build database. Very Web2.0.

In addition you can build similar systems for your spellchecker. Traditional Desktop spellchecker have the problem that they suffer from incompletion. A user needs to add a lot of words to the spellchecker before he can work with it, if we wants to write texts in technical language. If the user add vocabularys from his field to the spellchecker, he benefits from becoming the words that other similar users (who have similar words in their spellchecker) have in their spellchecker added to his spellchecker.