Fonts for Unicode CJK extensions C, D, E
The Hanazono fonts (HanaMinA, HanaMinB) have full support for all 3 extensions and include 96k+ glyphs. Here is the glyph list (.pdf, 500 pages).

Babelstone Han claims to support all glyphs in Extension D, but only has partial support for C (37.1%) and E (19.5%). 

EDIT:

Here's the download link (25.7MB) for HanaMinB (which supports these extensions). And here's a screenshot of a word processor with HanaMinB.ttf installed, displaying random glyphs from CJK Ext. E.