Really Useful Unicode – Geometric Shapes

⇒Lines See I

⇒Circles

⇒Ellipse

⇒Triangles – See Arrows

⇒Squares, Diamonds

⇒Rectangles

⇒Stars

⇒Misc

Lines: Many characters and combinations can be used to make lines. I find the following to be the most useful:
Asterisks: *****
Underscores: _____
—: —————
↔: ↔↔↔↔↔
∺: ∺∺∺∺∺
&#x22d8⋙: ⋘⋙⋘⋙⋘⋙
╱╲: ╱╲╱╲╱╲╱
╳: ╳╳╳╳╳
▁: ▁▁▁▁▁
▂: ▂▂▂▂▂
▃: ▃▃▃▃▃
▄: ▄▄▄▄▄
▅: ▅▅▅▅▅
▆: ▆▆▆▆▆
▇: ▇▇▇▇▇
░: ░░░░░
▒: ▒▒▒▒▒
▓: ▓▓▓▓▓
▤: ▤▤▤▤▤
▩: ▩▩▩▩▩
◀&#x25b6: ◀▶◀▶◀▶
◎: ◎◎◎◎◎
☀: ☀☀☀☀☀
★: ★★★★★
☆: ☆☆☆☆☆
☸: ☸☸☸☸☸
♉: ♉♉♉♉♉
♒: ♒♒♒♒♒
⚛: ⚛⚛⚛⚛⚛
⛺: ⛺⛺⛺⛺⛺
✈: ✈✈✈✈✈
✤: ✤✤✤✤✤
✱: ✱✱✱✱✱
✲: ✲✲✲✲✲
✳: ✳✳✳✳✳
✴: ✴✴✴✴✴
✵: ✵✵✵✵✵
✶: ✶✶✶✶✶
✷: ✷✷✷✷✷
✸: ✸✸✸✸✸
✹: ✹✹✹✹✹
✺: ✺✺✺✺✺
✻: ✻✻✻✻✻
✼: ✼✼✼✼✼
✽: ✽✽✽✽✽
✾: ✾✾✾✾✾
✿: ✿✿✿✿✿
❀: ❀❀❀❀❀
❁: ❁❁❁❁❁
❂: ❂❂❂❂❂
❃: ❃❃❃❃❃
❄: ❄❄❄❄❄
❆: ❆❆❆❆❆
❇: ❇❇❇❇❇
❈: ❈❈❈❈❈
❉: ❉❉❉❉❉
❊: ❊❊❊❊❊
❋: ❋❋❋❋❋
❌: ❌❌❌❌❌
❎: ❎❎❎❎❎
❖: ❖❖❖❖❖
⟷: ⟷⟷⟷⟷⟷
⟺: ⟺⟺⟺⟺⟺
⦓⦔: ⦓⦔⦓⦔⦓⦔
⧍: ⧍⧍⧍⧍⧍
⪓⪔: ⪓⪔⪓⪔⪓⪔
⿲: ⿲⿲⿲⿲⿲
⿻: ⿻⿻⿻⿻⿻
㞢: 㞢㞢㞢㞢㞢
ホ: ホホホホホ
🌸: 🌸🌸🌸🌸🌸
👄: 👄👄👄👄👄
💗: 💗💗💗💗💗
🔲: 🔲🔲🔲🔲🔲
🔳: 🔳🔳🔳🔳🔳
🔶: 🔶🔶🔶🔶🔶
🔷: 🔷🔷🔷🔷🔷
🔺: 🔺🔺🔺🔺🔺
😁: 😁😁😁😁😁
🚧: 🚧🚧🚧🚧🚧