40 CW is also a great place for QRP operation, mainly in the 7.030-7.040 section of the band. I have a little Mizuho P-7DX 600mW 40 CW portable with the optional filter. I love the thing and haev no problems making contacts with the rig running on penlight batteries, a straight key, a Mizuho KX-QRP tuner, and a wire thrown up in the trees.
I agree with Steve about 40 SSB, though. I worked a station in New Jersey the other day and got a very nice S7 report and disbelief that I was running 10W and a dipole