We are flying from USA to Greece and from Greece to Africa. Can i have some luggage send straight from the US airport to Africa so i don't have to drag them to Greece with me?
No. Due to the risk of terrorism (bombs in bags etc), plus more pedestrian concerns like customs clearance, airlines will not send passengers' bags unless the passenger accompanies them.
You could ship your bags ahead as air cargo, but this tends to be extremely expensive. One cheaper option would be to just leave your bags in storage at the airport in Greece.
There are luggage services that will send your bag to any destination you choose. They will arrange for your bag to be picked up from your home and delivered to your destination. Most work through UPS and FedEx, so the fees are similar to what you would pay if you walked in. They have an advantage over air cargo, as they have their own in-house custom brokers (in-house in FedEx and UPS that is) so bags will be cleared through customs with simple paperwork.