Extensions and plugins
Sometimes they get you past a brick wall; sometimes they add finesse.
Inkscape comes with a lot of extensions built in, and they are divided into categories. As with much of the Inkscape user interface, the extensions work in a way that is inconsistent with other areas of the program by opening in an independent dialog box. This is a shame because it would be nice to be able to quickly switch between extensions when experimenting with various effects. Extra extensions can be installed using the extension manager, and there are some additional ones on the website.