A handy tool - djv

A really great (free open source) tool for previewing image sequences is Djv. You can find it over at http://djv.sourceforge.net/. It sports very cool capabilities to cache them in the RAM and play them fluidly (even in FullHD). Djv runs on all 3 mayor platforms natively, Solaris is also supported.
Histogram, color picker, frame cycling, playback of Cineon and OpenEXR files and many other features are also at your fingertips, making it an all-around solution as an image sequence viewer.

Djv interface

And an added bonus: It's supported by Blender! You can set it as animation player in the user preferences, see screenshot below:

This way, every time you click on Render - Play Rendered Animation (or press CTRL F11), Blender opens the rendered frames and plays them back in Djv.
The only downside is that it seems it's not being developed anymore. But the feature set it already has justifies the download. Be sure to choose the development version - I haven't encountered any bugs with it yet. Let me know your experiences with it!