[frncscgmz]

Anyone knows of a similar tool for jpeg images?

[blacksmith_tb]

Jpegs are already lossy, but if you want to increase the lossiness (and decrease filesize)via the commandline, you can do that with imagemagick or graphicsmagick with the -quality flag on a convert.

[SquareWheel]

I use jpegtran for lossless. I've had good luck with http://jpeg-optimizer.com/ for lossy.

[d0ugie]

yeah, cwebp, works on jpeg effectively, gifs and pngs (pngs with a 30% lossless savings, much more if lossy), does some tricks pngs don't..