Simple extension which shows you if keyword exist or not. Tested only on OC 1.5.1 and 1.5.6.1 but I think it shoul work for all 1.5 versions. Success icon means keyword doesn't exist, warning icon means keyword exists.

EDIT: In version 1.0 I completly forgot to add support for keywords in Information, Category and Manufacturer pages, so I fixed it in version 1.1.

!! Enable permissions in System -> Users -> User groups for tool/keywordchecker !!