Essential home office software tools?

I'm relatively happy in my current job as a web developer, but I live in a provincial city in New Zealand where the IT market is unpredictable. At the moment business is booming but we've had some dark periods during the year and I'm thinking in my spare time I should put effort into setting up some sort of basic infrastructure at home to work on projects in my spare time or if I lose my job.

At work we use Trac for project management and TortoiseSVN for version control simply because we always have. Reading HN over the past few weeks has convinced me I'm a dinosaur. Because I work alone it can be hard to get a handle on what the new standards in the industry are.

My question: what would HN suggest as indispensable home office software tools -- for any operating system -- for the modern web developer? I work mostly in PHP but am not averse to learning a little Ruby. I am mostly thinking of version control systems (git?), project and bug tracking tools (Bugzilla?), development environments (Eclipse?), and anything I should be running on a home server (I am quite good with Debian boxes).

I would like to avoid purchasing new hardware.