I found a battered Linux book in a bargain bin at a warehouse store, and that was the end of the story...
These days, there are many more resources than there used to be. You can stick "linux" and just about any task in a search engine -- "linux command line" and the task if you want to find command line apps -- and find good tutorials.
Many will tell you that you don't need to learn the command line to use Linux any more, and they're right. You do need to learn it to be really good at Linux, though. It's not as scary as you may think! Type "man foo" to find out what the command "foo" does and how to use it. Pretty much everything has a man page. :)
The command line can be easier to learn that GUIs in a lot of ways, because telling people what commands to use is so much more straightforward than trying to explain what the icon they need looks like or where the right button is. Also, there's a Stack Exchange site dedicated solely to questions about Linux and Unix at http://unix.stackexchange.com/ I like it better than the Ubuntu one - http://askubuntu.com/ - personally, because the unix/linux site has more of a "here are the standard tools, and how and why they work" tone, while the ubuntu site's tone is more like "here is how to accomplish that task without having to learn more about the system than you absolutely have to". Both will get your task done, but the former will challenge you to learn more.
Edit: I almost forgot to add -- grab an IRC client (Xchat is good for beginners) and start chatting on the freenode.net IRC network. Many (if not most) big Linux-related projects have channels here, so there are many opportunities to get help with a problem, or just watch and learn. :)