That toolbar/ct plugin seems to cause problems for all who install it!
Close Safari, then locate and delete the following files and it should be gone:
/Users/<User name>/Library/Application Support/Conduit
where / is the root library on your Hard Disk.
If you are running Snow Leopard you should also look here:
Library/Application support/conduit plugins
Also, as mentioned by Gilli2000:
Library/Receipts - If you read it, it has information in it at the bottom referring extensively to "CT" and "community toolbar".
Maybe it is harmless, but trash those items anyway!
Note: Safari does not support any third-party toolbars except those supplied as an extension to Safari via the Extension Gallery.
If you are running Lion:
From the Finder Menu bar, select Go ▹ Go to Folder, and in the box that opens write:
Delete the second item if it is there.
Now select Go to Folder again and enter /Library
From the folder that opens, delete the following items if they are there (you may need your login password):
then close the folder. Now select Go to Folder again and write: /Applications/Toolbars
Delete that item and close the Finder windows you opened. Log out then log back in, and you should be rid of it.
I could not find any of these files even after showing hidden files. However, the problem I was having was with Firefox. I did find some CT and conduit files/folders in /Users/<User name>/Library/Application Support/Firefox/Profiles/<strangename>.default/. Try removing those. If that doesn't help, go to this site: http://www.2-spyware.com/remove-conduit-redirect-virus.html
(When resetting about:config values in Mac, it looks like you have to go one by one and context-click (rightclick).)