Searching visually and by reading level

A few times recently I've found myself searching and searching with students for good information. It has made me realize I haven't been modeling and teaching search skills enough for students to own a broad group of search strategies. These are two tools I'm really liking right now:

Instagrok is a visual search tool that creates a searchable mind map of ideas connected to your search term. It also allows you to search by reading level, gives key facts, and resources in various formats. (Thanks to Jason Kadonaga and his students for re-introducing me to this tool)

After seeing Instagrok found Google's reading level filters shown below. I'm not sure I would have listed this Encyclopedia Britannica article as "basic", but I did find some resources here that I was able to recommend to a student.

What search tools do you use? How do you teach search skills?