I use ImageReady CS using its droplets to make thumbs and all the other sizes too.
http://www.cleoslinks.com/crap/my_Im...y_droplets.zip
You need to have Adobe ImageReady CS which comes with Photoshop CS to use these.
Here is a list of more apps to make thumbnails.
http://www.versiontracker.com/php/se...acosx&x=13&y=8
iPhoto which is in your applications folder will also make thumbnails but wouldn't be my first choice.
More useful Mac stuff.
Having multiple clipboards to use while coping and pasting info/graphics/code/description/urls/etc. is very helpful.
CopyPaste
Batch renaming of files is also most helpful.
ABetterFinderRename
Batch watermarking images is another must have for me.
iWatermark
Knowing what time it is for other list owners can be helpful at times.
iClock