We don't currently deliver any extensions or toolbars for Internet Explorer. Internet Explorer doesn't tend to handle extras well, and most extensions available are not necessary, especially toolbars. In fact, if you are an IE user, you should probably look at removing Internet Explorer Extensions & Toolbars.
Due to certification issues, along with complex and unstanardised coding, we have decied to cease development on our Safari Extensions at this time. It is possible work will restart in the future, but even if it does, it may still be some time before our extensions are available for Apple Safari.
RockMelt was discontinued on the 31st of July, 2013, after being aquired by Yahoo!.