Adobe Lightroom

• Removing purple fringing
• Creating collages. Here's one that I did using these instructions.
• Set import and file handling preferences. Good for handling JPEG+RAW and also for automatically converting to DNG.
• Adding GPS data to photos from a tracklog

My Settings

Lightroom Catalog

• Automatically write changes into XMP. Records all edits to a photo in a separate XMP file. Good backup in case catalog gets corrupted.

Profiles

• Olympus OM-D EM-5 color profiles (or lack thereof)
• Universal Lightroom 4 OM-D E-M5 Preset by archeogeolab
• Lightroom 5 camera profiles

Presets

• Lightroom comments and some freebee presets for the OM-D
• Trey's Lightroom Presets
• Correcting CA

Plugins

Lightroom uses Lua for scripting. See Lightroom Development Center for the API and more details.

Jeffrey Friedl has lots of great technical posts on photography. Here are some relevant Lightroom posts:

• Jeffrey's Lightroom Goodies
  • Jeffrey's "Creative Commons" Lightroom Plugin
  • Jeffrey's "Picasa Face-Recognition Import" Lightroom Plugin

More plugins:

• Nik Collection
• Jeffrey's "Export to Facebook" plugin
• VSCO film filters