Sad to report that Icerocket, which has been around for years, is finally closing its doors. There's a note on the home page which says "Icerocket.com will be shutdown permanently on March 8th, 2017. Please switch over to other search engines. Thank you for all the years together!" No reason has been given for the closure.
On the other hand, Socialmention* has reappeared. I feared that it had died, but it's suddenly come back online, though what the story behind its comings and goings is I don't know!