Canon XT. 50mm f/1.8 II. Kenko extension tube set, all three tubes stacked. 68mm total extension.
It works, but it's not at all like having a macro lens. You lose focus to infinity. You lose focus much past a few inches, really. And you can only get the combination to focus at a very specific distance from the subject. So, a macro lens is still a better choice. But extension tubes and lens reversal are good inexpensive ways to do closeups until you can afford the macro lens of your dreams. I'd recommend extension tubes over close-up filters because there's no glass in extension tubes--nothing to degrade image quality. And both tubes and lens reversal will work well in combination with a macro lens when you get one.
Canon XT. EF-S 60mm f/2.8 USM Macro lens, with 50mm f/1.8 II reversed on the front of it (used a reversal ring to screw the two lenses together face-to-face by their filter threads).