Boom Crutch
For boats without a back stay, of course, there's always the "boom crutch". I've seen them shaped as an "X", with the boom in the crease, the legs in the cockpit, and the crutch affixed to the rear coaming of the cockpit. I have used a single crutch, which slides through a "U" bolt screwed to the rear coaming. It has an oar-like look, with a cut out in the tip of the "oar" for the boom to sit into, and is placed before dropping the main, and supports the boom while on the mooring all summer. I stained and varnished it, and decorated it with some line wrapped around it. It might be easier than installing a boom lift. Of course, you can hook something up to the backstay, if you have one.