This is a little one, but still really useful. There may be times that you need to add Web Parts to the default SharePoint list forms and you aren’t allowed to use SharePoint Designer. The most common reason you might want to do this is to add a Content Editor Web Part (CEWP) to the top of the page with some instructions for your users. If you try to go to Site Actions / Edit Page, you won’t see that available as an option.
If this is the case, just add &ToolPaneView=2 at the end of the URL and you’ll magically see the Web Part Zone with the Add a Web Part toolbar exposed.
You’ll go from this:
to this in a jiffy.