Pippin Williamson released a new plugin over the weekend called Transients Manager. You'll never guess what it does, but I'll go ahead and tell you: it lets you manage transients through the WordPress dashboard.
The way this plugin works is pretty self-explanatory from the screenshot. I think that's why I already know I like it so much. It tells you the name of the transient, the current value, a human readable expiration date, and lets you either edit or delete it.
This is a great one for your toolbox during development.