glowshi-ft.vim (GitHub: saihoooooooo / glowshi-ft.vim) by Shinya Saiho is a cool visualisation plugin for the
t motions. When a line has multiple targets, it display highlights and allows you to jump between them.
There are settings for changing the mapping behaviour, case handling, and timeout length.
Clighter (GitHub: bbchung / clighter) by BB Chung is a semantic source highlighting plugin based on Clang. It can do things like highlight occurrences of matching words under the cursor. It doesn't replace the built-in C syntax handling, but instead enhances it.