I just finished A Brief History of the Late Ottoman Empire - which is, as the title asserts, a survey of the last century and a half of Ottoman rule. The Ottomans fascinate me because of how long the empire survived - it was founded at the end of the 13th century, and survived into the 20th - which is a huge span of time. In that period they wiped out the last vestiges of the Romans (Byzantium), and then collapsed themselves in the wreckage of WWI.
The book covers the long period of decline, and - more importantly - how the Ottomans tried to deal with that decline. It's a sympathetic read - if you're looking for information on the Armenian Genocide, for instance, this isn't the place to look. If, on the other hand, you're interested in how they adapted to the steady rise of Europe and the industrial age, this is exactly what you want. I learned a lot about the "Young Turks", and how they were much more continuous with previous Ottoman politics than I had thought.
Why does any of that matter? Well, pull out a map of the near east, and look at all of the troubles the world has there. Never mind current politics - just realize that the map of that region was drawn by the victors of WWI, and then modified by the various successor regimes across the region as they consolidated their rule. Some of that consolidation is incomplete to this day (at least in the minds of the regimes dwelling there).
That's why the end of the Ottomans interests me so much. The empire spanned the time from the late medieval era into the 20th century, and the fallout from its collapse is still with us - just one more reminder that the past is still with us, whether we understand that or not.