We are big fans of Flat UI, and DesignModo have recently come out with what I would consider one of the best Flat UI Kits available. Created around Twitter Bootstrap, a reliable and proven tool for developers, the kit is completely responsive and works on a 12 column layout bases so everything fits together nicely, significantly simplifying the process of creating and developing your websites. The kit is available in 3 packages, the first for Designers and contains only Photoshop files, the second for Coders and contains the Bootstrap layout, and the third for you Front-End Developers, containing all of the above.
Flat UI Pro contains a huge number of basic components, icons and glyphs, which simplify your work when it comes to new projects. Don’t waste time reinventing the wheel, use Flat UI Pro to get started. Generate new ideas; design new projects. Spend your time creating, not building basic parts.
Did we mention that the pack kit also comes complete with 50 vector icons, 50 glyphs and recommended color watches specifically designed for use in flat user interfaces. Below is an image showing the brilliant collection of vector icons.