Is there an extension to give Safari the same multiple search engine functionality as Chrome? I have to admit, I never thought that I'd see the day I preferred a different desktop browser to Chrome. But with the latest release of Safari, I'm a believer. It (to me) performs faster, looks better, and having that baked-in sync functionality with all my iOS devices and other Macs is... well, insanely great.

That being said, there are a few features that I miss from Chrome, but the one that I really miss is the multiple search engines you could invoke from typing the name of them and then either Space or Tab (e.g., type "imdb" and then Tab to search using IMDb's search query functionality).

Is there some sort of less-advertised extension that I can get to bestow this upon Safari, or am I out of luck?
Try SafariKeywordSearch. It allows you to set up custom searches triggered by keywords preceding searches. For example, I have it set so that goto Ask Different uses Google's "I'm Feeling Lucky" to send me to the first Google result for "Ask Different".

There's a good set of built-in defaults, and it's pretty easy to add almost any site-specific search out there, by making a small edit to the URL. There are instructions on the site.