Wannabe

From my experience Photoshop’s “Save for web and devices” will give you the biggest bang for your buck.  It’ll give you the lowest file sizes with the least amount of artifacts.

However, one problem I had is that it’s difficult to resize a lot of images in bulk.  Especially if you want to compress images in sub directories.  After a lot of searching I came across this useful little snippet.  One thing – it’s only meant for .JPGs.  So any other format and you won’t be finding this so useful…but it might not be too hard to tweak.

To use this first download the script on your computer and open Photoshop.  Go to file>scripts>browse, select the script, then select the folder containing you .JPG images.

You can edit the file in notepad, dreamweaver, whatever.  To change to quality edit this line:
SaveForWeb(saveFile,90); // set quality to suit
Where 90 refers to the quality setting.

I also did some editing to this so it would also resize images before compressing them.  First find the line:
app.preferences.typeUnits = TypeUnits.PIXELS;
After it add:
doc.resizeImage(200, 133);
where 200,133 is the image size.  I think I did have some issues with stretching so check the aspect ratio beforehand.

Download the script here