I've been working with Umbraco for quite a while now, and I've become pretty familar with what it can do and how to extend it when it can't
After creating a load of membership extensions I started working on high performance search extensions. For when there is too much content for your average XSLT search. Utilising the Examine search and indexing framework that's been in Umbraco since 4.5 it's built on top of Luncene.Net.
I created autocomplete searches and flexible results pages allowing multiple providers and relevancy ordering. Then I started thinking about the indexer side of this and realised you can use it to index anything you want.
Out of that came the Umbraco Microsoft Office Document Search package.
Contact me if you think it sounds useful.