Chair braces are an easy fix for a wobbly chair. They're better looking and much stiffer than L-brackets. Most hardware stores carry chair braces in finishes like chrome, brass or bronze. To avoid splitting the wood, be sure to drill 1/8-in. pilot holes before driving in the screws.
If appearance doesn't matter, screwing a brace or T-plate onto a piece of furniture is often the quickest way to fix it. Adding metal may not make the piece totally sound, but at least it won't come apart.
Fix a Wobbly Table
If you've got a table that rocks on an uneven floor, you've probably tried wedging something under the short leg. Doesn't last, does it? Here's a better way: Use washers and nail-on glides.
First, drill holes for the nails with a 1/16-in. bit and install the glides. Then set the table in place and slip washers under the low leg until the table is steady. When you've determined how many washers are needed, pull off the glide and reinstall it along with the washers.