My Personal Code Style

Nonstatic member variables: m_lowerCamelCase
Static member variables: ms_lowerCamelCase
Local variables: lowerCamelCase
Constants: kUpperCamelCase
Parameters: lowerCamelCase
Enums: UpperCamelCase
Macros & #defines: SCREAMING_ALL_CAPS
Functions: UpperCamelCase for C#, and lowerCamelCase for C++
Classes: UpperCamelCase
Structs: lower_case_with_underscores
Braces: On their own line.
Whitespace: Tabs for indentation, spaces for alignment.
Iterators: i, j, k, etc, unless I'm iterating over a grid, where I'd use x, y, etc.

If I'm working on someone else's codebase, I'll follow whatever conventions are already in place there. I don't care what you use, so long as you're self-consistent. I don't want to see a codebase that's at war with itself.