I thought I had posted an entry on Charles at some point. Apparently not, but Charles is a proxy that I've used in the past to help debug web services calls. At the time when I first started using it, Microsoft's Fiddler wasn't (IMO) ready for prime time. More recently I've checked out Fiddler2 and have switched over to it. If you need to debug web services, particular those involving communication over SSL, it's a quite handy tool.