Generating HTML documentation from WSDL

What are your approaches to generating some sort of human-readable documentation from WSDLs? In the past I've used WSDL viewer (by Tomi Vanek) and I'm happy with the results, but I'm interested in any possible alternatives.

I've also heard of x3sp, but I haven't tried it.

Solution

I tried several alternatives

TechWriter for Web Services: Really powerful, but HTML output was (see comments) multi-file. Also, comments indicate it is retired, but that is no longer the case.
<oXygen/> XML Editor: It doesn't process embedded schema.
Altova XML Spy: It doesn't process anonymous types.

and ended up tweaking WSDL viewer to my needs.