I mostly use Google. MSN Search, despite my antipathy to most things Microsoft, brings up different results for the same search, so, it comes into play. VIVISIMO‘s CLUSTY is a crawler with a useful concept: it catalogues search returns by category. There are others like it of course.
However, even if it isn’t the first search box out of the toolbox, there is no cooler search interface than that of KARTOO, as far as I know. You need Flash; check it out.
When I googled “all known search engines” The JafSoft Search Engine page came up. It doesn’t seem quite up to date, but it is being updated, (an important distinction to make). …more reports to follow from ol’ Sherlock.