ToolPac (from DotSoft) is an enormous collection of tools to make your Autocad life much easier. My philosophy with Autocad (and software in general) is that you should never do anything that is repetitive or inefficient if it can be helped. That’s where ToolPac shines. If there is anything that you can think of that is repetitive or annoying about Autocad, ToolPac probably has a good solution for it. A lot of the “tricks” that I use are from ToolPac. I don’t want to go into detail here, simply because I don’t know where to start. Seriously, there are dozens of little tools in ToolPac.
This is an essential add-on for Autocad. I would never seriously do a lot of design without this. I don’t merely recommend this tool; I require it.