As other users, I've had trouble getting deluge to work. I un-commented the corresponding entries in the S00custom-options text file and rebooted (by removing from the power plug) the WDTV Live, but I could not get a deluge link to appear in the web interface. The same thing happened with nzbget.
Additionally, I discovered that enabling deluge somehow killed the functionality of the cd-manager. WDTV Live could no longer read data from an external USB DVD drive. Disabling deluge (from the S00custom-options text file) seemed to solve the problem.
I finally managed to get both deluge and cd-manager to work. I traced the problem back to my WDTV Live settings: I've had entered a custom IP in Settings -> Network Setting -> Network Setup. Once I selected "Automatic" instead of "Manual", everything worked immediately (Well, almost everything. I still can't eject disks from the DVD drive without cycling the power in both the drive and WDTV Live).
Since my custom IP settings were correct, there must be a bug somewhere that prevents some functions of the WDLXTV Live firmware to work when you are not getting your IP from a DHCP server. After you boot with automatic IP settings, you can change them to manual again. Just be certain that when you boot WDTV Live, it uses automatic IP settings instead of manual.
I thought I'd post this in a separate topic instead of the general WDLXTV Live thread, so that people who have trouble getting deluge to work can find this post easily and won't have to go through the hours of frustrating trial and error and slogging through dozens of forum pages that I did.
P.S. As a newbie, at first I had trouble understanding that when you read somewhere in the forums that you have to reboot WDTV Live, it means that you have pull the plug out of the device, not just put it to sleep mode from the remote.
Everyone takes it as granted, but new users will probably be confused by this. So I'd thought I mention it here, in case it's of use to some other newbie.