Many mail order dealers sell the Ektachrome 100D Super 8 cartridges. B&H is just one that I know of. Processing is standard E-6 and can be done at Dyanes if you don't have a local dealer who can arrange it.
The other super 8 films are Tri-x B&W reversal and several Eastman colour negative films. The colour negative film is almost always scanned to video. The Tri-x will probably need to go to a movie lab.