Bootswatch is a library of themed swatches for use with Twitter Bootstrap. It allows the time-constrained and design-impaired to give their Bootstrap sites color without having to open a color picker.
Visit http://bootswatch.com.
Replace Bootstrap's default bootstrap.min.css file with the one from your chosen swatch.
Swatches are created in LESS. Modifications are made to the existing variables.less and with the addition of bootswatch.less.
The files can be found in the gh-pages branch here. You are welcome to fork the files and modify them further.
Please send bugs, submissions, and other feedback to feedback@bootswatch.com. For more information, visit http://thomaspark.me/2012/02/introducing-bootswatch/.
Thomas Park