Every once in a while I run into something I need to debug from the network up. Most of the time I can do this using Wireshark but there are a few instances where what I'm really looking for is a man in the middle proxy. I usually find an alternative way to debug what I'm working on but recently I decided to find a combination that worked so the next time I can use it.
Most of the time what I'm working on when I need a proxy has something to do with SOAP and there is actually a MITM proxy in SoapUI but it doesn't have support for HTTPS. If you are working with SOAP and can use HTTP then SoapUI is a great tool. If that doesn't fit the bill then Paros proxy does a good job.