Sleeves are one of the most basic forms of cases available, and United SGP's Illuzion for iPad 2 ($60) doesn't stray far from the formula. A simple leather envelope, Illuzion has enough room to hold the original iPad or the iPad 2 with or without Apple's Smart Cover attached. Available in eight colors designed to match Apple's Smart Cover choices, all but one are built out of a very soft, very thin glossy cowhide with a microfiber interior; the exception…
