I've been invited over to a new colleague's house on Saturday for a BBQ and it turns out it's also her daughter's 17th birthday. I can't turn up empty handed but haven't the foggiest what to get her, plus I'm working all week so have limited opportunity to get to the shops 
given that I don't know them that well I'm thinking a voucher is probably safest but I don't even really know what kind of shops late teen girls are into these days! Can anyone suggest a safe option??