> Besides graphics/imlib, I also found graphics/gocr and print/magicfilter to
> build fine without the netpbm dependency.  Haven't yet tested their
> functionality without it though.  
> 
> Unfortunately textproc/subtitleripper can't seem to do without netpbm...  

It can, actually; it will write pgm files without the ppm library. 
(You just have to undef _HAVE_LIB_PPM_ in the Makefile or in the
compile line.)