"One more thing," in emails

• "As an aside ...," in a text
• "Oh, also ...," in a text
• Start of a texter's aside
• "Oh, before I forget ...," in a text
• "Oh yeah ...," in a text message
• "You can tell a lot about someone ___ they use abbreviations": Peter Serafinowicz
• Texter's "Oh, and ..."
• Start of a modern afterthought
• "Incidentally ...," to a texter

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
Internet abbreviation of by the way , in use by 1989.