Ubuntu LTS tend to backport a good number of packages. For example, if you wanted a fairly recent nginx, you will find 1.4.x built for 12.04 LTS https://launchpad.net/~nginx/+archive/stable

Is there a benefit to using the nginx PPA rather than nginx's official repos[1]?

I use Debian Stable with several upstream repos, and I've never understood why people use a PPA when upstream provides a repo (e.g., nginx).

[1] http://nginx.org/en/linux_packages.html

The particular packages you need might be obtainable from Launchpad PPAs, which Debian doesn't really have an equivalent of unless you're willing to maintain your own.

If you don't want to phase-in updates rather than depend directly on a third-party PPA, you can also setup your own PPA and copy packages to it as you wish.

The packages at release are more up-to-date, and the official backports repos are filled with newer versions.