Here's a versatile conveyance called the trioBike that can function as either a bicycle alone, a stroller, or a combination of the two. You can drop your kids off at day care, leave the stroller there and ride your bicycle away.
We were completely sold on this idea until we discovered that the complete system with bike and stroller together costs 2587, or a jaw-gaping $3318.57. Ouch.
Product Page [trioBike A/S]