I've been building custom kernels for most of my computers lately.
Yes... computers. Like many geeks, I have a few computers. Some of them are good, some of them not so good. They all do something.
canberra, my oldest so-called modern computer (and by modern I mean capable of running a *nix operating system), has been busy for two days now building a kernel. As I type this, it's rolling into hour 49 and it's still not done. The cool thing is that this modest computer (486sx25 with 32 MB of RAM and ISA slots only - no PCI or other such modernity!) is chugging along just fine. The metanetwork IRC network has a server on canberra, and it's still responding just fine without noticeable lag.
I almost threw canberra away once. As a Windows machine it wasn't much use anymore, so I dismantled it to scrap it. I never got around to finishing the project. When I discovered Linux and started getting curious about it, canberra was the only computer I had that was no risk to try Linux on, so I put it back together. I've upgraded it a little since then (added some RAM and a SCSI card, and more storage space) but it's essentially the same machine.
Not fast, but reliable. That's why it's still powered up. 201 days of uptime too! :)