Like Sandbox, Particles is another WordPress theme that is designed to be built upon with extra features and design elements. Particles is maximized for dial-up users:
4 Seconds or Better – The Particles theme has loading time of 4 seconds or less on a minimum connection speed of 56K.
These meta-themes are great for getting the general layout of your blog the way you want it and then adding in the elements that you want – or hiring a designer to brand it for you.
Full features, description and download.