Use marking menus... you can make your own or use the existing ones. Shift + RMB + swipe down is extrude. Very handy. Shift + RMB + Up has a couple options for merge vertices and Shift + RMB + Down/Left is Insert Edge loop when in object mode. You can watch my tuts on marking menus here: https://www.youtube.com/playlist?list...MFeIkJc58OChNN

If you really want hotkeys, most of the regular buttons are taken, but you can usually find ctrl+shift+key. Semi-colon is free.