SmartTag Maker will allow you to encode regular NFC tags to behave like Sony Xperia SmartTags. This allows a lot more options in terms of form factor, stickers, bracelets etc. Perfect for if you have a Sony Xperia S.
Note: You will need the app Xperia SmartTags installed to use your new tags.
Check out my other apps for things to do with your shiny new tags, specifically Car Mode On.
This app is in no way affiliated with Sony, I just really like their products.
On a related note, while I am in no way affiliated with www.rapidnfc.com, I have had nothing but good experiences as a customer.