I wrote a script to create trello cards from questions on SE sites. This was really for me more than anything else because I use trello to help me keep track of things I'm working on, which sometimes include feature requests and bugs raised on MSO. An auth redirection will happen the first time you try to use it, but after that it should work as you would expect. Formatting is preserved, and cards can be created on any of your boards and can be given a (single) label.
See the demo video for usage.
The script can be found here: https://gist.github.com/aggieben/5811685