Text

Biblia Hebraica Stuttgartensia without critical apparatus
Westminster Leningrad Codex available in different formats (facsimile, text only, translation, etc)
--The author has furthermore encoded the results of Richard Elliott Friedman's work in the Documentary Hypothesis, allowing the display by color of the various Pentateuchal sources. This on-line version uses the SBL Hebrew Unicode font and it supports copy-and-paste of Unicode text from the browser into an appropriate word processor
Aleppo Codex - click the "view" button on the left to see a high res of the scroll.
Sefaria
Bar Ilan Responsa
Otzar HaHochma
Leon Levy Dead Sea Scrolls Digital Library
Digital Dead Sea Scrolls. - pretty straightforward.
Interlinear Samaritan Pent: an "amateur" site, but a dedicated one with helpful comparisons to MT, morph, and english translations
STEP Bible from Tyndale House (has many, many search capacities and sources; also Samaritan Pent)
Shebanq: somewhat complex, but accurate analysis of the tagged biblical text (OT).
See also: Text Criticism section below.

Audio

Hebrew Audio (other) recorded by Abraham Shmuelof (other)
The Bible (Tanach) recorded by Shlomo Bertonov (IMO a better recording, but costs $$)

Fonts

Accordance Font new Unicode font
Hebrew Unicode font by SBL; best font I have found for positioning all diacritics correctly
Tyndale House Unicode font
Apparatus SIL Unicode font by SIL for text criticism sigla
The Brill Unicode font but beware of usage restrictions

Lexicography

Semantic Dictionary of Biblical Hebrew by United Bible Societies
KLY Database Utensils in the Hebrew Bible by Johannes de Moor, Bob Becking, and Marjo Korpel of the Het Oudtestamentisch Werkgezelschap

Text Criticism

TC: A Journal of Biblical Textual Criticism
OT Text Criticism Blog: Online Digital Manuscripts and Editions

Teaching Helps (all ages)

Animated Hebrew flash download of Jonah comic, can change scripts and languages; other resources for teaching
Exegesis Guidelines a well categorized "library guide" from Southern Baptist Theological Seminary (good Text Crit section)

Extrabiblical

Inscriptions of Israel/Palestine
Epigraphic Hebrew fonts free; not Unicode; utilize BibleWorks keyboard
A Bibliography of Semitic Linguistics (1940-2010) by Gregorio del Olmo Lete


Modern Hebrew

Grammatical Index for Hebrew from Scratch
Vocab Flashcards for Hebrew from Scratch

Lexicity links to online language resources including Hebrew—not sure how useful it is