Here's a great (and growing) list of free or freemium board games online that a friend shared with me!

Document version: https://docs.google.com/document/d/10iOD7Wy_YU4NmkPU7ZH7YTrq...

Spreadsheet version: https://docs.google.com/spreadsheets/d/1FnsE0E3p_qVugf2Tu6dj...