Add new calendar appointments to clients Outlook from webpage

I have a website (ASP.net MVC2) where a database stores data/times of events. I want a client to be able to log in and sync these items to their Outlook. Is this at all possible? I've had a look around but haven't found anything useful, other than this isn't possible in javascript as that would open up all sorts of secur开发者_运维知识库ity holes snooping through users' registrys... If not, I may have to look into basic alternatives such as downloading xml documents with the event details.

We do it with Exchange Web Services, but that is only for an Intranet application.