From the author of "Math Library for Unity"
http://u3d.as/content/dest-studio/math-library-for-unity/6tp

Forum topic:
http://forum.unity3d.com/threads/234595-RELEASE-FREE-Primitives?p=1557127

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Package contains 15 procedural primitives including:
- Box, WireBox, OutlinedBox
- Quad, Plane, Disk
- Sphere, GeoSphere
- Cone
- Cylinder
- Gengon
- Tube
- Torus
- Arrow
- and finally classic Teapot!

Creating primitives as easy as dropping prefabs to the scene (Prefabs folder contains all the prefabs). Then just change the parameters. It's also possible to save meshes to the assets. All primitives except for the arrow have uv coordinates.