Here are a few cool features I like to use when cleaning up my drawings.
1. laywalk command. This command basically walks thru all the layers and displays any object on that layer. If you double click on a layer, that layer will remain on while you continue walking thru other layers.
2. -overkill and overkill command. This command allows you to remove and combine overlapping linear lines, plines, and delete unneeded duplicate copies of objects. In addition, it allows you to change the numeric fuzz value.
3. Other command that most of you might be using and have read about in other post, blogs and forums are: -purge, purge, scalelistedit, recoverall, audit and mapclean.