It wasn't long ago that a 22-inch monitor for under $200 was cause for celebration. Now I'm just waiting for them to dip below $150. In the meantime, Buy.com has one the best deals I've seen yet: an Acer X223Wbd 22-inch widescreen LCD for $166.99 shipped. No rebates, no refurbs--these babies are brand new.
CNET hasn't reviewed this particular model, but there is a product brief if you're interested. It's a pretty basic LCD, with a 1,680 x 1,050 native resolution and 5ms response time. Inputs include both VGA and HDCP-compliant DVI, the latter important if you plan to watch certain DRM-protected content (like Blu-ray movies). Alas, it lacks speakers, but that's hardly a deal-breaker: most monitors that have them sound weak and tinny.
A dozen or so Buy.com buyers collectively rated the X223Wbd 4.5 stars out of 5, and I'll cop to being perfectly pleased with the 22-inch Acer that's been on my desk for two years. If you're looking to expend your screen estate on the cheap, it doesn't get any cheaper than this (yet).
Update: Wait, wait, hold the phone. Turns out it DOES get cheaper: TigerDirect has a 21.6-inch LCD, with HDMI and speakers, for $149.99. That's plus shipping ($15-ish) and after rebate ($30), but still.