Q:

List of inverted letters and their applications

Upside-down letters, as in ∀, and left-side-right letters, as in ∃, are used in mathematics and logic to indicate for all and there exists.  Do you know other examples of such inversions in other fields. Is there a name for the practice? 

A:

There are many other examples in mathematics alone, and the answer will depend on what transformation you allow and what font you choose.  For example do / and \ count as transformed I's?  The schwa (ə) for phonetics comes to mind. You might want to check out the full IPA symbol list and the unicode block of letter-like symbols, U+2100 through U+214F, which contains several turned letters. Various languages use transformed Roman characters.  For example Cherokee has a backwards J.

A:

LaTeX, used by mathematicians for typesetting, has \mho \Game \Finv meaning respectively  Ω G F rotated 180°.  Presumably these are used in mathematics...

