The sweet little 5-inch monitor that Sony introduced at CES 2011 is now in stock and shipping for $399.
The CLM-V55 has a clip-on attachment for mounting on Sony Alpha hot shoes or a standard hot/cold shoe as found on other DSLRs and camcorders. The 5-inch display has a 800 x 480 resolution and offers a 1:1 zoom to full HD images. It connects via HDMI and sports a headphone jack so you can monitor audio as well.
Find the CLM-V55 here on B&H.