i wrote a script for the IMacros add-on in Firefox if you want to save all the comics you've done. when you open it in the sidebar, just edit and save #Current.iim as:
VERSION BUILD=7031111 RECORDER=FX
TAB T=1
SAVEAS TYPE=JPEG FOLDER=C:\Comics FILE=+{{!NOW:mmdd_hhnnss}}
TAG POS=1 TYPE=IMG ATTR=SRC:http://www.stripcreator.com/images/rightarrow.jpg
WAIT SECONDS=20
SAVEAS TYPE=JPEG FOLDER=C:\Comics FILE=+{{!NOW:mmdd_hhnnss}}
TAG POS=1 TYPE=IMG ATTR=SRC:http://www.stripcreator.com/images/rightarrow.jpg
WAIT SECONDS=20
---
just make sure you create the C:\Comics folder first. if you want to change the folder to something else, just make sure you use <SP> instead of spaces
then just go to the first comic in your collection, set the repeat macro number to something high like 5000 (it will automatically stop when it's done) and then hit Play(Loop)
this will capture the whole page, comments and all, but could probably be improved on (by someone better than me) if you wanted to just capture the png. takes about a minute for every 2 comics so give yourself some time