Please identify the most popular lightweight markup languages and compare their strengths and weaknesses. These languages should be general-purpose markup for technical prose, such as for documentation (for example, Haml doesn't count).
See also: Markdown versus ReStructuredText
I know of three main languages used commonly in the greater programming and tech community: Textile, Markdown, and reStructuredText. All three can be learned in a couple of hours or "winged" with the cheat sheet nearby.