When it "absolutely, positively" has to get there, don't be so certain it's Federal Express or UPS that is going to get it (whatever it is) there first, not with the recent launch of NextJet. The Dallas-based, Internet-enabled start-up guarantees same-day (instead of overnight) service for those who need the fastest delivery going and are willing to pay for it. By using a business model that relies heavily on the Internet, the company books existing carriers for its shipments, and has no inventory of airplanes to warehouse and maintain. NextJet plans to cater more to business customers, but everyday consumers who want something in the last minute--caviar from Iran, Maui Wowie from Hawaii--can get the service by paying the fare.