I've been going on and on about ADO.NET technologies for the last few days, so now it's time for something completely different...
Over the last couple of months, I've realized that Microsoft Excel deserves much, much more love than I typically give it.
It all started when I saw my beloved spouse, who's not of a technical inclination, do some serious data scrubbing by using Excel to modify data from SharePoint lists. She was doing text manipulating and cross-referencing tables like nobody's business, all with zero programming knowledge. I know I would probably have decided to whip something up in C#, and of course it would have taken far longer to code and verify.
Next, I went through a few very good books. I can't recommend Microsoft Excel 2007: Data Analysis and Business Modeling enough. It walks you through a number of general-purpose useful features of Excel for managing data and crunching numbers, then goes into different techniques to tackle different business problems (many of which are readily adaptable to working with technical problems).
The next bok was Charts and Graphs for Microsoft Office Excel 2007. I'm a developer - suffice it to say that anything I can do to improve the aesthetics of my output is welcome.
Last but not least, you should check out the Microsoft Excel blog, which has all sorts of good stuff from formatting tips to programming examples and more.
And I haven't even touched upon the programmability stuff, or some old projects where I would generate Excel XML spreadsheets to consolidate data from all sorts of sources, and on and on...
Clearly Microsoft Excel has a lot more that I barely know about, and the loving will grow. A big shout out to all the teams involved with it and all the customers that help shape the product!