I'm out on a limb here ... but when i did this (and there is a good chance that i did do it the long way), I used a mysql data base to store the data and got the software to interface with the database.
What I'm guessing is you want an interface to remove the issue of writting it yourself.
This link seems to be along the lines of what you want:
Aside from this Google turns up "evolution data server" which is capable to serving to several programs besides evolution.
Actually - I had a look at the IBM thing and it looks pretty decent and comprehensive. You do have to sign up, but it's free and you don't have to give them info besides your email ...