The MC's or toasters of the reggae dancehall's have always been one of the most important parts of reggae music. Many top dancehall artists started and continue to be reggae DJ's.
Some of the greats of the past like U-Roy, Shabba Ranks, and Yellowman brought the reggae DJ out into the light. The styles of the MC's vary however it seems that dancehall is the usual flavor. Today some of the biggest names in reggae are out in front of the DJ world like Beenie Man and Bounty Killer. Many of these artist start out as a DJ then with time begin to sing to the various reggae riddims and when they get good enough the people ask them to perform. These few have convirted from DJ to Sing Jay.
Links
Reggaebeat.com - Reggae playlists.