As biz said, your post lacks specifics. If all you need is the ability to charge some ancillary lipos up to 4S, you can pretty much take your pick. You just need to decide what your budget is and whether you want AC/DC only.

Without knowing your budget, I would strongly recommend the Turnigy Reaktor. It will let you charge your 4S at a pretty good clip, but it might be a bit overkill for what you need. If your budget is less and you don't care about how quickly you can charge your 4S, there's the Hitec X1.

Neither charger requires a power supply.