If you have the means, the space, and the transportation, ladder track dollies are a great solution for camera movement. Rod shows how he's picked up a set of ready-made 'bolt on' dolly wheels to a simple plywood board to create an 8ft dolly capable of carrying a good amount of weight. In smaller more confined situations a slider is a must, but there's plenty of benefits to using a wider platform for stability in your shots.
These dolly wheels are designed to run on pipes as well, but when possible using a Ladder will provide a very firm solution that can be laid out in just about any type of terrain (gravel, grass, mud) and still maintain a super rigid track - unlike long PVC pipes. In this older article you can see how a ladder was used for a DIY Timelapse rig: http://cheesycam.com/diy-motion-controlled-timelapse/
If you're intersted in building your own dolly system, you could try some angle iron and at least 8 skate wheels + bearings, but if you're slightly off in drilling it's going to cause you quite a bit of wobble. To make things easier, these wheels that Rod is using are an inexpensive solution.