C

C, the language

psyclpc and libpsyc are in C, and a few other things in the software list.

psycpp also provides a little parser in C.

See also libpurple.

C++, the language

Dyskinesia and psycpp are in C++.

Some orphaned projects too, such as libPSYC and PsycM.

C#, the language

psyconaut is a .net application in C#