No offence anyone, ( I'm sort of with the " natural " look ) I (personally ) think those nails look sort of stupid. Perhaps I wouldn't mind the clear or black ones, but the colourful ones just make me think the people have the pet as a fashion accesory. ( pet peeve: people that have small dogs as fashion acsesories and have them wear humiliating things like little pink skirts
http://petoftheday.com/i/our_smilies/mad.gif )
I'm also not sure how well they would work. As has been mentioned, the cat's nails would grow, you would have to keep re-glueing the things on. Personally, I'd just cut 'em once a week and place a scratching post in my house somewere.
I hope no one has found any offence in this post because none was ment