The Sigma Super has a wireless E-TTL mode. You can setup multiple slaves on multiple channels and set ratios between groups of slaves. I have tried to use this feature with one master and one slave, and found the performance to be unreliable. Either I'm doing something wrong, or the Sigma wireless E-TTL system isn't near as good as Canon's. I always give up in frustration.
However, the built-in optical slave of the Sigma Super works very well. I have often used one unit on the hotshoe in manual mode (no preflash) to trigger another unit in optical slave mode.
If you want to follow the strobist philosophy of multiple manually-adjusted flash units, the Sigma Super will work as well as any other unit, though at a higher cost than a Sunpak 383 or Vivitar 285HV.
I generally carry two flash units in my bag - One Sigma Super, and one Sunpak 383 with a slave attachment. With this combo, I have many options for flash, including E-TTL, traditional automatic, manual, and optical slave. The only combination that won't work would be E-TTL flash on the hotshoe with an optical slave.