Humane text processors
Easy to read and easy to write Textile and Markdown, generate valid XHTML markup from plain-text documents, using simple conventions:
h2. Shopping list
Buy in nearby grocery
* Potatoes
* Tomatoes
* Onion
* Zucchini
Shopping list
Buy in nearby grocery
- Potatoes
- Tomatoes
- Onion
- Zucchini




Markdown
Originaly by John Gruber and Aaron Swartz, allows for basic HTML formatting. PHP Markdown and BlueCloth (aren't ruby names more appealing)
Textile
Developed by Dean Allen, supports tables and richer formatting. TextilePHP and RedCloth for ruby.