Flutterby™! : home BGA soldering?

Among other things over the past year I've been playing with Linux on a couple of different ARM processors in some fairly large dev kits, and as an exercise I've been thinking it'd be fun to lay out a small ARM based Linux machine, something like the Gumstix devices. The problem is that the chips I'm most familiar with are BGA parts. I've seen lots of notes on soldering surface mount devices with leads, have friends who've done it, but I know that even commercially it's hard to get BGA devices soldered right (and one of the reasons I know this is that some of those dev kits had flakies that went away when I pressed on one of the BGA devices...).

Anyone know anything about soldering BGA devices at home? In a toaster oven or on a hot plate?

And while I'm asking for the impossible, I know that two layer boards are fairly cheap, I was thinking that I could do four layer by just doing two two layer boards and running traces through holes between 'em. This would also let me put components on both sides. Yeah, the overall assembly would be thicker (two boards plus a gap for insulation in between), but it'd be cheaper than a 4 layer setup. I think. Comments?