I code in Python, Ruby, C++, and, to my regret, Java. Java is particularly painful to code in given its verbosity (cmp Python / Ruby) and lack of power (cmp C++). Unfortunately, Java has a strength: its libraries. Thus, I've been coding in Jython and JRuby as well. Definitely recommend them; Java's libraries have their strengths.
On my list to learn:
- C# (from what I hear, C# is Java with much of what I hate about Java replaced with wonderful stuff, and many other things added in)
- Haskell / Scala (some functional language)
Random esoteric languages I can code in:
- Befunge (93 / 98)
Personal favorites of my Q/A