I'm wondering if there is a website that collects (and hopefully updates) information on available web services.
Edit: Thanks for all the info; many good answers. I can only accept 1 as the "accepted answer" at this time, so I picked my favorite one.
Not really a web site, but you can use UDDI to find information on what web services are offered by businesses that publish service listings. There are several client implementations listed at the bottom of the page I linked to.
Back when webservices were going to take over the world, I stumbled upon xmethods.net. It's still around, but I can no longer vouch for it's accuracy or timeliness. Note the dated blurb:
Emerging web services standards such as SOAP, WSDL and UDDI will enable system-to-system integration that is easier than ever before.
Googling web services list points to a couple higher rated sites that you'd probably want to check out as well:
Personally, I've discovered that random, free web services are more trouble than they're worth. Pretty much anything they're doing*, I can more effectively and more reliably provide myself for minimal cost.
If I'm looking for a solution to a specific problem, eg. storing credit card data securely, then I'll evaluate the options in that space - web service or not.
How about http://www.programmableweb.com/apis? It has a fairly large list of popular Web Services and a quick info sheet on each, including how to access it.
NOAA provides a great (and free) collection of weather webservices that you can use,
Seekda.com for "Big" (WS-*) services only, based on WSDL/SOAP. Let me know if you've found it useful.