This site is good for every type of teacher including information on different lessons, videos to share and many other teacher resources.
The one I bookmarked is specifically for spanish but other subjects are listed
This is a Web-base of 101 mathematics problems that are searchable by keyword or by categories. The site provides a bibliography of sources, and an explanation of the categories listed on the search page. Some of the areas of mathematics that can be searched are geometry, algebra, probability and statistics. Another category included is types of thinking which includes reasoning, process, and puzzle problems.