A quick summary of the content available on the XDA-Developers wiki.

automated summary

• front page
• popular categories
  • most child pages
  • all categories
• popular pages
  • most read
  • most edited
  • most linked-to
  • longest
  • protected
  • all pages
• popular images
• overall activity
  • statistics — number of pages, users, and edits
  • recent changes — project namespace, categories
  • Mediawiki version & installed extensions (official version history)

manually-chosen

• categories
  • Category:Guide
  • Category:Software
    • Category:Android software
    • Category:Cooked ROMs
    • Category:Official ROMs
    • Category:RomTools
  • Category:Navbox
  • Category:Storage devices
• pages
  • flashing guide
  • recovery partition
  • FAQ
  • ClockworkMod Recovery
  • partition SD card (needed for apps2sd)

The VAST majority of pages are about a specific device, so it can be hard to find non-device-specific pages. Some are listed here:

• acronyms and glossary
• generic Android head unit — for use in a car dash
• Android Development Codex
• microSD High Capacity
• how Android packages are signed
• NANDroid

PC software that's used to flash a phone:

• nvflash
• ADB
• Odin

Bootloader stages and partitions:

• recovery partition
• bootloader