Legendum is a typeface not unlike MS's Verdana. It has been made for optimal screen readibility. It is anti-aliased on Windows as well. It now contains all normal Latin characters as well as all Greek characters, plus punctuation. All are instructed. I use this permanently on my desktop, and have found it extremely nice to look at for longer stretches of time.
It has the OpenType features "kern" (kerning), "lnum" (lining numerals; it's got old-style numerals by default), "mark"/"mkmk" (mark positioning). It comes in two flavours: Legendum_legacy.otf has hundreds of precomposed characters (such as é) while Legendum.otf does not, but OpenType-aware OSes and/or applications may be able to produce them anyway. The file for the latter is a lot smaller though. Most of the Latin combined glyphs are there, and (I think) all of the Greek ones (including polytonic Greek).