High resolution images of the Aleppo Codex (ca. 930 CE) as well as information about this highly important Masoretic Bible. Also available as a PDF download.
This Hebrew language site provides the ability to read the Hebrew Bible in a number of ways, such as with or without verse numbers, with or without vowels, and even on a scroll without verse dividers (תיקון קוראים). The text is based on the Aleppo Codex.
This site allows you to compare the Hebrew Bible side by side with translations in Old Greek, Latin, English, and a number of other languages. Hyperlinks to the Brown, Driver, and Briggs dictionary too.
"Signs, Symbols, and Abbreviations Used in the Hebrew Text Critical Apparatus" by Paul Tanner. The Biblia Hebraica Stuttgartensia can be purchased here.
More than a century old, this dictionary is still a fantastic resource for biblical lexicography. Online at ericlevy.com or available for download at archive.org.