Windows Desktop Search
Not to derail the conversation (as if...), but I was absolutely stunned at the brilliance of WDS this morning. I've got a Tablet PC that I've used regularly over the past year for taking meeting notes, etc. I installed WDS on it a while back, but had never really used it. So I fired it up this morning and tried searching my archive of documents. I've got about 130 Word docs, 15-20 Excel files and some random other items.
First, every search I tried completed in about 0.1 seconds (the UI actually tells you this, and the results are visible faster than you can blink...). Not only does it list each matching file, it also shows a preview. You can filter by different file types, and you can also modify the indexer to specify by file type what kind of information to index - properties vs content, for example. Because of the slow rate of change, indexing has no impact on performance - in fact, it explicitly only does indexing during "idle" time, and there are only a couple of items at any given time that need to be indexed so it finishes quickly.
Now here's the really brilliant part. I use OneNote quite a bit, and WDS even searched within my hand-written notes to find matches. Is that f'ing brilliant, or what? It even gives a "confidence" score of how accurate the match is.