Richard Ishida, of the World Wide Web Consortium (W3C), has created what he calls “small web-page utilities” to aid in language use online: a Unicode database viewer (“Look up characters, character blocks, paste in and discover unknown characters, store your own info about characters, search on character names, do hex/dec/ncr conversions, highlight character types, etc. etc.”), Unicode character pickers (“Pickers allow you to quickly create phrases in a script by clicking on Unicode characters arranged in a way that aids their identification”), and a Unicode Code Converter. (There’s also supposed to be a Language learning test app, but it doesn’t seem to be available at the moment.)
On the other hand, if what you need is a keyboard to write any language from Akan or Albanian (Shqip) to Xhosa or Yoruba, try Gate2Home:
This site enables you to write in your language wherever you are in the world, with an online onscreen keyboard emulator. The main purpose of this site is to let everyone who gets stuck without the ability to write/type/search the internet in their own language be able to do just that (usually travelers/tourists or anyone in front of a foreign computer).