Update: deviantart updated their interface. This still works, thank God.

hateeyes, that earlier bug regarding the journals has been fixed, so you shouldn't need to change anything. just make sure you have my version of deviantART Big Thumbnails, the link is below.
in addition to removing the small thumbnails, this also gets rid of the page jump that occurs because the script replaces a class name and the style is applied post-display causing element heights to change.
Because of the bugs artis pointed out, I took a look at the issue and decided to write a modified userscript instead, which makes the thumbnails on non-standard pages large as well. The userscript is found at http://userscripts.org/scripts/show/3508 and this userstyle is pointless without it. Note: if you have the original deviantART Big Thumbnails script installed, uninstall it. Mar 19, 2006 - slightly improved script at above address is up that improves the resizing of the shadowed background.