
I will start the ball rolling with some that I have thought of or heard about. Some are copybot specific, others more general.
*****
Set your land to 'no build' - not just shops, your home land as well if you can. This not only prevents 'opportunist' copying of your products, doing this to your home land will protect anyone else's builds you own on there.
Unlinking smaller parts of a build then putting a complete copy inside the remaining part. Purchasers buy 'contents'. Again, just trying to make it harder for thieves.
Do your building near your shop where possible - this allows you to keep an eye on customers (descreetly, I don't like being watched whilst I browse, and I am sure lots of other people don't either). If you see two people, one of who is pushing the other around, and the pushed one is a) brand new and b) has no groups or details on their profile, you are reasonable suspecting it is a bot. Say hello, (in IM if you are not in sight) and if there is no reply you could try IMing !quit to it (this no longer works for all versions of the bot).
If you see the above occurring in someone elses shop, notify them and keep an eye on the suspicious couple. If you see them start to create a copy, AR them both and take a photo - if we all work together on this we can make it harder for copybot to be used anywhere.
Similarly, if you spot an item in a yard sale or shop that you suspect is something made by another creator - firstly, take a deep breath!
Check the creators name (if you can't see this in edit, be sure you don't have 'select only my items' turned on). Is it the person you think it 'should' be?
If you can go see the original do so, are they really the same? Take a photo of the suspect one and send it and the location to the original creator. If you are really sure you are looking at a copy, report it. Be careful, we do not want to start 'witch-hunts'.
Add your name and the date at the edge of textures you create for SL. This could prove useful against certain other content-theft tools. It is also good practice for any artist.
Keep master copies of all your creations - this way you will have the earliest dated one if there ever comes a time when you need to prove you are the creator. Including creation information on one or more of the component prims is also a neat precaution - you will konw that your chair's leg has the date in it, who else will? You could also add a notecard to every new build with your info on it. Once you start this - and do make sure you know when you start this, all future builds will have to have this included to be authentic ones. Copybot doesn't copy contents, remember.
Including a small logo on clothing or other texture based builds puts one more barrier up for the would-be thief. Whilst we know there are ways they can rip your texture, this gives them editing they would have to do and therefore slows them down. Many theives are opportunists and anything that can make them think twice is a good idea. Either have your logo as part of the look (like your name on the pocket patch on a pair of jeans) or a tiny version tucked away somewhere - you will know where to look for it if a debate ever arises!