Thanks for your wonderful project! I have added ClearType rendering to WinDjview along the lines of http://www.grc.com/cleartype.htm. I have uploaded the modified source files to http://ifile.it/iksjqox All modifications are commented by my initials, C.H. The mode is switched on when the "HQ" option is turned on, which is an overlap of sorts. So, if you decide to include this feature in future releases please add a separate checkbox.
I've also found another project that has the same goal: http://code.google.com/p/windjview-subpix/. It actually produces sharper images compared to my version, but the chrominance of the b/w rendered text is not controlled very well (for the curious: it does just one of the two smoothing steps described on the grc.com web site above). On the other hand, it sharpens both b/w and color pages. So, choose for yourself.