Antipas Christadelphians: Handel's Messiah Mi
Complete libretto, commentary, nearly complete MIDI.
George Frideric Handel - Messiah
Libretto; WAV files of several movements (at Classical Music Pages)
Handel's Messiah
Complete libretto, with sources.
Handel's Messiah Through the Centuries
Paper by Patrick Findlay: related musical and cultural changes.
Inkpot Classical Music Reviews: Handel Messiah
Introduction; recommended recordings, some with very detailed reviews.
Karpeles Manuscript Library - Handel's Messia
[scans of two pages of a historically interesting manuscript]
Messiah by George Frideric Handel
Digital facsimile of complete score (1912 Schirmer ed.)