I have heavy Profoto battery packs, but when I want to travel light and don't need so much power, I have an Elinchrom Ranger Quadra RX pack, spare battery, extension lead and a couple of heads, which I'm very happy with.
The heads are very small and light, have a daylight balanced LED model light. They have a slot for an umbrella and take a few of their own modifiers, or with an adaptor, you can use the full size Elinchrom modifiers. The packs are 400W/S with an asymmetric split, also come with built in Radio skyport.
Personally, I can never get on with Speedlites, strobist style, I find it all a bit of a bodge. The Quadra suits me just fine, although not as compact as just Speedlites, the pack is still relatively small and light.
http://www.elinchrom.ch/product/Ranger-Quadra-RX.htmla review here:
http://elinchrom.s3.amazonaws.com/press/docs/bjp-quadra-review.pdfI guess the other obvious suggestion comparable to this is Lumedyne, but I think the Elinchrom is more sophisticated.
HTH