Rich text editor
Online Markdown editor with support for sync to Google Drive or Dropbox, publishing to Blogger, GitHub, Tumblr, SSH server and others, plus loads of Markdown extensions like fenced code blocks, smart punctuation, table of contents, MathJax, sequence diagrams and flow charts.
ASCII Flow Diagram Tool. Export plain text diagrams
Sublime Text 2 theme, designed for Mac. Has accompanying colour scheme.
iPad code editor with GitHub and Heroku support
Mac note-taking app that syncs with Simplenote. Lots of Markdown features - fork of Notational Velocity from the author of Marked
Highlight text and a hovering contextual toolbar pops up over your paragraph. Useful for markup/links.
SVN/Git, project panel (instead of drawer), display folders first and other tweaks
Slick database diagrammer for Mac. Will also generate DDL and other database functions
TortoiseSVN style information within Textmate’s project drawer
Makes searching in files much faster
Essential if you’re working with a non-local project
Textile toolbar that can be added to Rails apps
IntelliJ IDEA for Ruby/Rails development