If you want to stay on the OO path, I would suggest Smalltalk (Squeak), or the simple but powerful Io programming language (http://iolanguage.com/ http://iolang

If you want to stay on the OO path, I would suggest Smalltalk (Squeak), or the simple but powerful Io programming language (http://iolanguage.com/ http://iolanguage.com/). C is also an important language to learn if you don't know it already. You could use it to implement a simple database for a very specific task (http://cr.yp.to/cdb.html http://cr.yp.to/cdb.html)