More symbols

Would want a way to get to way more symbols. Mathematical symbols, IPA-symbols, Greek letters, currensy sumbols, arrows, and lots of other from ASCII, Unicode and so on.

I often find that I need special symbols for typing equations. In such list, all symbols avalible in the system should be avalible, regardless of the language being used at the moment.
The interface for this does not need to be in the usual keybord layout, but could simply be a huge scrollable table.

At the moment, I am forced to change to a different app, copy and paste, such symbols.