Unfortunately, it may not be that simple. According to a forum post at Mozilla, these toolbars may not be as simple, or as benevolent, as they seem. According to this post, user information is collected and sent to the Conduit servers. Users are not informed, and it is likely that the library "authors" of the toolbars are also unaware of it.
I don't know how accurate this is or whether there is something that the library creators of these toolbars can do. I haven't seen anything in the forum replies that negates the basic premise of the post. I almost created a similar toolbar when I first heard about Effective Brands. I was unable to get onto their site at the time (I think they were changing over to the Conduit name and servers). I never went back to the idea.
I would be interested in hearing from anyone who is using one of these library specific toolbars. Are you aware of any user data being collected? Is there information to that extent during the toolbar creation process? (If you use a toolbar from your local library, you may want to ask the library about it. Point them to this post or the Mozilla forum post for reference.)
(By the way, folks, I'm sure that a post like this is likely to generate lots of "this is the best thing since sliced bread" comments. I'm considering these to be advertising. I'm not interested in how great your library toolbar is--the concept is great and I'm sure all the toolbars are useful. Something can serve a good purpose using a bad method. I'm concerned about the data collection, so comments that are just "gosh-wow" or links to toolbar sites will be deleted.)