Image Picka is a fantastic app! When downloading from a forum or DeviantArt, I open each image in a new tab, then use Picka to download them all.

*The only qualms I have are:
1. The difference between this and DownThemAll is where Picka requires a thumbnail page to be generated first. This becomes an issue when a forum or image site has all of their images inline or directly linked, resulting in waiting for unnecessary thumbs to be created for hundreds of images.

2. Upon saving all of the images, the extension tab closes. I would prefer if it added a checkmark or colored the thumb border to signify that it has downloaded successfully. Otherwise I'm left guessing which ones made it.

3. I have to leave all tabs open after the process finishes because I've experienced where Picka closes the tabs but didn't save some images.

Despite all this though, Image Picka is very easy to use and is always in my toolbox, along with the likes of DownThemAll, Noscript, and Search by Image (Armin Sebastian).

Definitely worth 5 stars!