OS X 10.4 comes with keyboards and fonts that let you type and read modern and ancient Greek. Fonts which can be used are Lucida Grande, Helvetica, and Times, and they should work in any Unicode-savvy app from Apple or other parties, including Office 2004 (which also includes two additional fonts for modern Greek). Two apps which cannot do Greek without special add-ons are AppleWorks and MS OfficeX.

Apple's Polytonic Greek keyboard is missing the ability to create oxia acute accents and can only make the tonos variety, which may cause problems with some fonts, including Lucida Grande in Tiger (but not in Leopard), that have slightly different glyphs for these two identical diacritics. The other layouts listed below, except GreekKeys, can do oxia.

Some sources of additional Greek Unicode fonts:

http://socrates.berkeley.edu/~pinax/greekkeys/NAUdownload.html

http://scripts.sil.org/cms/scripts/page.php?site_id=nrsi&item_id=SILgrkuni

http://scripts.sil.org/cms/scripts/page.php?site_id=nrsi&item_id=Gentium

http://www.evertype.com/emono/

http://www.scholarsfonts.net/cardofnt.html

http://www.geocities.com/greekfonts/

Some sources of additional Greek Unicode input keyboards:

http://www.sourcecod.com/sophokeys/

http://faculty.bbc.edu/rdecker/font/mackeyboard.htm

http://socrates.berkeley.edu/~pinax/greekkeys/GK2005.html

http://homepage.mac.com/thgewecke/fs/FileSharing9.html

For doing non-Unicode Greek in programs such as WordX or AppleWorks:

http://www.vodkatini.gr/XGreek.shtml

Fonts designed for doing Greek with older non-Unicode apps will likely be encoded as ISO-8859-7 (ELOT-928), Win-1253, or MacGreek, and these may not be usable with more modern Unicode apps.

Special Sites: Some websites of interest to users employ non-standard Greek encodings. An example would be

http://bible.crosswalk.com/Lexicons/NewTestamentGreek/

To use such pages you need to download and install the special fonts indicated on the site. You may need to try different browsers and wordprocessing apps to get satisfactory results.

Sites of possible interest:

http://www.macephemera.gr/
http://www.rainbow.gr/
http://www.helmug.gr/
http://www.hri.org/fonts/mac/