Keeping with the Unicode/font theme, here is the announcement of the latest release of the useful Junicode font package. Although it focuses on Medieval characters (Correction: and *does* now cover polytonic Greek) is has very good coverage of Latin, symbols, ligatures, as well as Runic, etc.
Junicode 0.6.13 is now available at http://junicode.sf.net. Here are the release notes:
This release continues to add characters from the MUFI recommendation to benefit medievalists. Many messy outlines have been cleaned up, improving efficiency and reducing the likelihood of bugs. Most of the goodies in this release are for users of OpenType-aware programs such as InDesign and XeTeX: the OpenType features list has been thoroughly worked over and rationalized, and consistency imposed across all four faces (though it is still true that there are more OpenType features in Regular than in the other three). Use of ccmp, mark and mkmk has been greatly expanded, making use of combining diacritics more practical than before. Many MUFI glyphs have been made accessible via OpenType features, especially ccmp (for glyph+diacritic combination) and hlig (Historical Ligatures). Fractions, Roman numbers, subscripts and the various “Enclosed Alphanumerics” have been made accessible as ligatures (either liga, Standard Ligatures, or dlig, Discretionary Ligatures).
Junicode absolutely does cover polytonic Greek. Have a look.