Every doctor I've ever been to as well as my pharmacist tells me that antibiotics (although only certain ones, I'm not sure the difference) will lessen the effectiveness of the birth control pill. The pharmacy even puts a sticker on the bottle.. ya know, one that says "Take with food" and then one that says "Lessens effectiveness of birth control pills" :P.
The one that stands out in my mind that they always are sure to mention it'll hurt is azithromycin. Although, to be fair, all I can find is that it "may decrease", never that it "will decrease". Either way, I'd rather be safe than sorry!
and then go to the interactions tab.)