1. As others stated, many of the fonts highlighted there are totally useless for world users at large because of their lack of Unicode coverage. The western font design community should really stop thinking the ASCII block is all that matters. No matter how cool they are, a font that only includes about a hundred glyphs is a toy.
2. DejaVu is not bad at all, especially if you use the Freetype autohinter (and not insist like some distros on using the patented bytecode interpreter)
3. Google Droid should be noted too
4. TEX and especially GUST have some good fonts. Unfortunately they don't make a lot of effort to check their licensing, making inclusion in law-abiding distros hard (the Gyre fonts are a very unfortunate example)
6. Many of the font problems users experience on Linux are due to:
- lack of fontconfig support in some apps (causing crashes if a specific font is missing)
- bad fontconfig support (QT/KDE apps often hit by this)
- lack of support for a modern font shaper (pango/cairo): openoffice.org/java...
- old fonts in legacy formats not converted to modern TTF or OTF containers (Type1 fonts are especially bad, as they often need 10s of entries in font lists to do the same job as one opentype font)