SSMSBoost add-in (currently free)
- keeps track on all executed statements (saves them do disk)
- regulary saves snapshot of SQL Editor contents. You keep history of the modifications of your script. Sometimes "the best" version is not the last and you want to restore the intermediate state.
- keeps track of opened tabs and allows to restore them after restart. Unsaved tabs are also restored.
+tons of other features.
(I am the developer of the add-in)