Bittorrent Client
- Bittornado, uTorrent, BitComet
Irc
- mIrc
Browser
- Internet Explorer, FireFox
Archivers
WinRar, Winzip, etc
(Some manga viewers can run these independant of these softwares)
Useful Series Update Sites:
http://www.mangaupdates.com/
http://www.manganews.net/ (No Licensed Stuff )
http://www.dailymanga.org/
Manga Archives:
http://www.blubbblubb.net/manga/ (New releases, HTTP)
http://www.tidwah.net/ (HTTP)
http://www.animewaves.net/ (HTTP, Has lots of series :S)
http://gotlurk.net/ (IRC, Biggest Archive I know)
http://www.sosmanga.com/ (HTTP)
http://www.mangaspot.com/ (HTTP)
http://stoptazmo.com/ (HTTP)
http://boxtorrents.com/ (BT)
http://silverado.mindwerks.net/ (HTTP, Update Site)(BT)(IRC)
http://souhaku.ufpag.com/ (HTTP)
http://www.tokyotosho.com/ (BT)
http://www.animenow.org/ ( Craptacular HTTP )
http://www.animenow.org/~k-manga/ ( :O K-Manga Releases)
Manga Viewers:
ACDSEE - Not Free :(
CDisplay - http://animenow.org/files/cdisplay.zip
Manga Viewer - http://animenow.org/files/MangaViewer.zip
Ifran? - http://www.irfanview.us/
I find these are the common viewers people use to view their manga. I could be wrong. Some people might prefer to open 1 image at a time in the archive file





especially together with a info site so you know you get all chapters 
