Twitter Bootstrap is a toolkit from Twitter It includes base CSS and HTML for typography, forms, buttons, tables, grids, multi-level navigation, success messages, warnings messages and error messages and much more

Blueprint is a CSS framework that gives you a solid foundation to build great looking websites! Blueprint offers the following

• A CSS reset that eliminates the discrepancies across browsers.
• A solid grid that can support the most complex of layouts.
• Typography based on expert principles that predate the web.
• Form styles for great looking user interfaces.
• Print styles for making any webpage ready for paper.
• Plugins for buttons, tabs and sprites.

formee is a veyr cool css framework that allows you to create very sexy web forms and warning/success messages

52Framework is a CS3 framework that features box shadows, border radius, text shadow and box/text/rotating and more