Contributing to an Open Source project is a fantastic way to learn new skills and gain some real work experience. Unlike most of the work done in the proprietary world, the contributions you make to a Free Software project are generally publicly visible and thus can easily be included in a portfolio you show to prospective employers.

In most cases, getting involved in an existing project is quite easy. Most projects need help and would be very happy to count you on board even if you're not a developer. Good places to start:

• the operating system you use (e.g. Ubuntu or Debian)
• a piece of Free Software you use every day

Of course, if you can't find a project that solves your own particular problem, you may also want to start a new one. You may be surprised at how many people will find your pet project useful and see a community grow around it.

I gave a presentation on this topic for the New Zealand Summer of Code.

Here's how to tell how much space (on disk) a Postgres database takes:

SELECT pg_database.datname,  
       pg_size_pretty(pg_database_size(pg_database.datname)) AS size  
  FROM pg_database;

Thanks to Matt Clarkson for the tip.