Stylus for the the i500 and earlier tablets: http://www.tabletkiosk.com/tkstore/pc/viewPrd.asp?idproduct=47&idcategory=24. This does not work on the i535 screens.
Magnetic digitizer pen for the i535 tablets: http://www.tabletkiosk.com/tkstore/pc/viewPrd.asp?idproduct=186&idcategory=24. This also works on the i500 and earlier screens.
BasiQ tablet stylus: http://www.adonit.net/jot/mini/
The Adonit stylus originally sent with BasiQ tablets has a looser tip connection which tends to come off, so we have since replaced it with the second options.