Best software for tensor manipulation?

[nuclearhead]

Do you know any good software for manipulating tensors: varying Lagrangians, checking gauge and supersymmetry transformations, etc. ? One that could deal with anti-commuting variables would be good too. One that also supplied group constants for SU(n) etc. would also be useful.

I was also looking for some simple software that knew that AxB +BxA = 0 for cross products of abstract 3-vectors but couldn't find any.

 

[Greg Bernhardt]

Here is a nice list to browse
http://en.wikipedia.org/wiki/Tensor_software

 

[nuclearhead]

Well yeah, but I was hoping for some reviews from people who used them.

I see Mathematica has TensorExpand which is something anyway.