Ocelot, their custom-made C++ tracker is a nice piece of code.
They were forced to drop out php-based and XBTT-based trackers some years ago when the server load from their became huge peer swarm became unmanageable.
Combined with AdBlock, I use Ghostery[1], which is a nice add-on (Chrome/FF/Safari/Opera/IE) : it blocks any javascript from ads networks, but also from analytics, trackers, socials plugins (and more) , and also cookies from the same trackers. Everything is configurable per-tracker and per-website.
It's quite a must-have if you don't want to be the product on the Internet. And a good failover over Ad-block.
Nginx works very well with PHP-FPM through FastCGI, and there is about zero configuration needed as everything is up and running after an apt-get (minus some commented configuration regarding php in Nginx).
I think more and more php-based app are powered by this kind of stack.
TorrentFreak made a great story about this[1].
[1] http://torrentfreak.com/what-cd-debuts-lightweight-tracker-f...