Chrome: Ctrl-F is one of the top keyboard shortcuts everyone should know. If you need to find more than one word at a time though, Pearls Extension helps you find everything at once.
The extension allows you to enter multiple search terms across the page you're on, all pages on a specific domain or across all sites. Each term gets its own colour, and the searches are remembered even after you leave the page. The extension defaults to searching for exact matches (so, searching for "hack" would not highlight "Lifehacker"), but you can toggle between exact and partial matches.