Coporate level content management systems / intranet systems that aren't community portals and that don't cost the earth.
This is something close to my heart since I've been involved with the development of several bespoke solutions now and the evaluation of dozens of 'off-the-peg' applications that all promise the earth but so often fail to deliver.
Many utterly fail to deliver a fully flexible system - most actually try to force the client users into using the features they supply rather than supply a raft of features that can be activated if required from the control panel.
Given the relative ease from a software engineering point that this can be accomplished I am still amazed that so few products offer a simple series of web forms that allow the user to customise CMS database fields to their own requirements, using the base engine to run things but allowing naming conventions to be controlled (within reasonable limits) by the client to meet their own requirements.
I know I'm going off on one here but as an example, the college I lecture for was quoted horrific amounts for their intranet system and CMS. Their solution was to design and implement their own applications in-house, using the skills they had to hand. I was heavily involved in that project from the very beginning and the end product is entirely geared to actual requirements and it was developed at a fraction of the cost of any third party solution.
The database design, scripting and interfaces could all be worked out in the languages you mention and the entire project is more than complex enough to keep any final year student up all hours ;o)