In a nutshell, sketch cards contain a hand-drawn picture right on the card. They can range from doodles to pieces worthy of hanging on one's wall. Because they're drawn on the card, Topps has been marketing and labelling them in their non-sport sets as 1/1s. But beware. It's the sometimes the same tactic you see on eBay everyday with a knob listing their card serial numbered 100/100 as a 1/1 because it's the "last one printed."
Case in point: here's a sketch card I pulled earlier this year from Indiana Jones Heritage drawn by Ryan Waterhouse:
Now check out here, here, here, here and here. There's a few hundred (possibly thousand) Waterhouse monkeys out there. Thankfully as the bar has been raised in the last year by other non-sport manufacturers, doodles like these are becoming rarer. But with Topps entering a new realm in sports where many "collectors" go ga-ga over anything marked 1/1, I worry some might get duped. But if Topps' first promo shots are any indication of what's coming, I'm excited for something new. Here's the pictures I was sent (I'm pretty sure the artist is Brian Kong):
Topps' re-launch of sketch cards begins with 2008 Topps Updates & Highlights Baseball. They're a hobby exclusive falling two per case. They're also on tap for 2008 Stadium Club Baseball at a rate of one in four boxes.
There's plenty of aspiring artists out there looking to make a name for themselves. That's what makes sketch cards so appealing to card manufacturers. They can create gorgeous inserts for a relatively cheap price. The artist may not make a ton up front (they're taken care of, but not by much) but by getting their work out to the masses, the exposure can lead to more lucrative work, not to mention direct commissions to collectors that usually run anywhere from $10 for a black and white pencil sketch to $100 or more for a full-color piece.
Like most everything else in the hobby, sketch cards can be great or they can suck. Hopefully the quantities and quality will remain in check and they won't become overkill like they're quickly becoming in non-sports.