UPDATE (January 25, 2011): Sunday downloading is broken with this version; use 0.0.4 instead.
Now taking up more memory than ever (350MB this time)! Profiling suggests that parsing the 400KB information file is somehow taking up all of that memory. I might switch to some kind of CSV/plain text database thing if it continues to eat up memory like this
Also, I've added Comic High!'s web comic offerings to the list. Unfortunately, the downloaded files are low resolution (around 600x800), but that's not my fault.
I haven't gotten the chance to add Famitsu yet, but it's just PCViewer, so that should be easy.
Online Manga Downloader 0.0.3 (4SH)
Leave bug reports, suggestions, etc. in the comments or in the github repo.