Radegast offers the ability to save textures (that you have perms for, of course) from your inventory to disk.
Currently it does NOT give you the same ability to save pictures from your 1st/2nd life profile tabs or Picks tabs.
NOTE: http://jira.openmetaverse.org/browse/RAD-299
(the ability to locate a profile picture in your inventory) would mitigate this need a lot if it's implemented, though it would still be nice to have a "save" option on the picture itself.
Thank you. 
Radegast is great and we appreciate all the amazing work you do on it.