I joined a company that was unionized, 30% wage increase. For software engineering work.
I am theoretically represented by the Metalworkers Union (IG Metall), despite never having machined any metal in my life. When I first started this job, I balked at the "restrictions" (strict 10 hr/day limit, 40 hr/wk contract, no Sunday work without permission from the main Works Council for the company), but after a few years, I cannot imagine going back to life without them. The six full weeks of vacation is pretty ace, too. Germany requires employers to give 24 days; the Metalworkers Union negotiated and maintains 30.
I should probably join them, or at least send them a nice gift basket. They've helped make my life here pretty comfy.