Here's my Ti RSP proline which i'm using for work transport until the thing sells...but I have run slicks on pretty much all my MTB's from time to time. Why? Because amongst other things, knobbly tyres are awful on tarmac,and there's lots of that round my neck of the woods
My 85' Team Stumpjumper (salvaged frame and used 88' Rockhopper components) I put the semi-slicks on because I do a lot of road riding and light urban trail use.