Share 'Frugal garden ideas?'

Matt just did a nice breakdown of some frugal gardening suggestions by Treehugger. How do you keep it cheap? For me, the big one is starting my own seeds. And saving some of them. I also like to salvage other people's yard waste - especially leaves. And I've gotten nearly free compost ($25 per truckload) from a nearby organic dairy farm, just by asking.