It's one of the browsers based on the Chromium project. According to its website http://www.slimjet.com, it keeps most of the features available in Chrome while adding a bunch of extra features to make your life easier or do things faster. It also adds more options to make it more customizable than Chrome. Notably, its toolbar is customizable and you can add/remove buttons just you do it in Firefox.
I've tried for a couple of weeks and so far it lives up to their claims. I like Chrome's speed and reliability but its lack of options is always a turn-off for me. Slimjet does satisfy my desire to customize and optimize. It has direct support of URL alias which is a big plus for a keyboard junkie like me.
I guess people who are interested might check it out and share your thoughts.