Bought a Smart Case for my mini and added a stylus holder to it, like I knew I would before I bought it (been doing it to cases for ages).
For anyone who wants to do the same, here's the basic recipe:
*Get an elastic band from a local store, hobby stores and such should carry it.
*Cut a piece off that is just shy of long enough to fit your stylus when in a loop, without stretching.
*Burn the edges of your cut to prevent frayed edges, then use a needle and thread to saw the piece into a loop.
*You should now have a complete loop that stretches to fit your stylus snuggly
*Glue the piece to your Smart Cover. Super glue is normally quite good at bonding these two materials together, and you can use a bottle with a brush for better precision. Once you have secured it, you can apply some around the edges of the mold to secure it even better.
*If you want you can use some Sugru(.com) to merge the case and the band a bit better, but remember that the band stretches.
Disclaimer: Gluing something to a $80 case means that $80 case won't be as new afterwards. Should you ever decide to remove the mod it will leave a mark, probably tear off the top layer of the leather. You could maybe try double sided tape or something like that to see if you like it first; personally I've had iPads for so long that I'm no longer in any doubt as to how useful this mod is to me personally.