A miscellaneous thought for the day: Given enough time, what (non-computer) background processes do you run in your everyday life? Letting the dishes soak to get out a tough stain, or letting clothes air-dry?
If you have the time, these processes are very cheap yet effective. People who don't have the time pay for extra products to make these processes go faster (a powerful dishwasher, chemical cleaning products, or clothes dryer). It's the old cliche - time is money. Software development is the same way. Being able to just kick off a background process that does work for you can be a great way to increase productivity. It's like being able to do two things at once, such as integrating your code (continuous build on a build server) and doing local development, or running a local pre-checkin script to verify for unit test errors and reading a design doc.
It gets especially cool if you have access to other machines (or virtual machines), and you can kick off more than two things at once - like having a database integration test run on Machine X, performance tests run on Machine Y, Static Code Analysis / Unit Test coverage run on Machine Z, all while catching up on email.
All this really requires is the desire to multi-task, and the hardware to do it. Given that a computer is much cheaper than a developer, if one is multi-tasking properly, it could be well worth the investment