Apollo Soyuz launches. The first International Mission carries on-board some neat swag and one Super Florida mosquito!
List of items carried can be seen at CollectSpace. The soyuz launched first with Leonov and Kubasov. After Slayton, Stafford, and Brand launched aboard their Apollo, Slayton was noted to say, "Man, I tell you, this is worth waiting 16 years for". Finally being cleared for flight after being grounded through the Mercury and Gemini programs with a heart condition, Deke was in space and became the oldest man in space at 51 (of course the record later fell when Glenn flew on STS-95 at the age of 77 on Space Shuttle Discovery).
During the extraction of the Docking Module and numerous maneuvers for rendezvous, Brand asked Capcom Truly to tell the launch crew at the Cape that they had permitted a stowaway to board the spacecraft. "We found a super Florida mosquito flying around here a few minutes ago." Slayton said that he planned to feed it to the fish that they were carrying onboard if he could catch it, and Brand wanted to bring it back and give it astronaut wings. But after flying about for several hours, the mosquito was never seen again. Apparently, it died in the reduced pressure pure oxygen of the CSM. Full day's events here.