Offermatica seems to be the industry leader in landing page multivariate analysis but I just found out about another tool called "Memetrics". This is a tool owned by Accenture and uses their Choice Modeling methodology.
They claim that Taguchi, which is a linear alogorithm is not the best way to predict human behaviour. Choice Modeling takes into account trade offs and preferences. Taguchi in a linear design and is a fractional factorial science which does not understand content interactions. While using Taguchi, enough sample for 16 versions of the page are required. Memetrics and choice modeling requires only enough sample for the number of attributes that will be tested and can then run a full factorial test in less time with less sample at a higher degree of confidence than Taguchi or Optimal Design (by Optimost) can.
Memetrics is the only tool which can easily optimize multiple outcomes, weighted outcomes and even offline outcomes. Memetrics is the only solution that is not a black box but rather a fully exposed, open analytical framework.
I personaly have not used Memetrics but it seems like a new technology that can be used for Multivariate testing.