Glossary - Common error messages and terminology
X Transitions - Explanation for "installing xserver-xorg-core would break existing software"
i855 is Unsupported - Explanation of why i845, i855, i865, etc. chips aren't supported
Non-Graphical Booting - Running X manually, without gdm
Wireless Without X - How to get a wireless network connection without X.
Direct Wired Without WAP - How to connect two laptops with direct ethernet cord.
Crashes and Freezes
X Backtracing - How to collect a backtrace for an X crash
X Crash Fixing - How to fix X crashes
Interpreting GPU Dumps - Ringbuffers, batchbuffers, and the meaning of intel_gpu_dump output
Valgrind - Debugging memory leaks
X Bisecting - Using bisection techniques to solve regressions or backport fixes
X/Testing/Touch - Touchscreen and multi-touch testing
X Quirks - Fixes for some common hardware-specific issues