When booting the Debian installer via PXE (see the relevant chapter in the Installation Guide for how to setup DHCP/TFTP and where to download the necessary files), the next logical step is to use a local Debian mirror in your network.

Using the entry in the proc-Filesystem of a running process, it's easy to get a sorted list of environment variables for a certain process ID (PID):

tr '\0' '\n' < /proc/<PID>/environ | sort

Since the lines in environ are null-terminated, putting proper newlines in the output with tr is necessary before sorting. (sort can only output lines terminated with \0 using the option -z, but not read them, besides: even -z doesn't quite work as expected in my case)

Oh, this comes in handy:

vimdiff /path/to/file scp://remotehost//path/to/file

Damn, how many features do I actually know of vim? (thanks, Mika for pointing this out, there's even a blog post about it)