C++ is a *big* language. It depends a lot on what you need... Indeed, the Stroustrup book is a good reference, might not be what you need...
One very cheap book is `thinking in C++' reasonably good for learning some OO concepts, and dirt cheap (available on the net for free). As far as `interesting' C++ books go, I will still recommend Scott Meyers _effective C++_ stuff, and Herb Sutter's _exceptional C++_ series (you can start with the _Guru of the week_ series on internet. (as far as I'm concerned, Herb's book is still the definitive reference where exception handling is concerned). There is very little that's unix specific in these books. As far as using C++ on unix goes, I would recommend learning some qt, and looking at all the fine applications available in the ports tree, a lot of stuff based on qt or kde is fairly decent, and highly interesting as far as modern C++ style goes...
