I think you are running in to a bit of a language barrier here, I'm guessing you are looking for speedlights (flashguns) for off camera use.
If you are shooting a fairly dark environment with umbrellas, you want full automation and you have a flash that can act as a master the canon 430 is a good good choice. For everything else there are better options out there.
In the cheap end of the hobbyist market the excellent Yongnuo YN560III flashes reside. They are manual only and have a built in receiver so you don't have to rely on the optical triggering the canons would use. You can get a trigger called rf603 that will let you trigger your EX550 with the yongnuo flashes. This set up will be fully manual and you will have to adjust the power on the flash as it stands at the moment but there is a new commander unit coming out in a couple of months that will let you change power remotely. You can get four or five of these for the same money as one canon flash.
At the other end of the spectrum you have the canon 600ex rt which will do full automation with radio triggering and lots of other goodies. If you have the money for it these are probably the speedlights most people will want.
Sorry for my poor english!
A product in the middle - between the 600ex rt and the Yongnuo - is the product I am looking for. The Nissin i40 is very compact, so i thought it would be a speedlight that can be easily used as an accent-light.