Symbaloo

Edshelf describes Symbaloo as  " a customizable start page tool that lets users add all their most important links in a format that is easy to use. The user’s webmix appears as sleek buttons with icons or logos. The user can drag and drop items to organize them in a way that is convenient and practical. The items, or tiles, can be searched so users can find those that are most relevant to the items they are adding. "

Here is an example below.  If you are a science teacher, you might have your physics tiles coloured red,  your chemistry tiles coloured blue etc. To see their website, click here.