I'm a big fan of the VMware Labsflings. Flings are described by VMware Labs as "...a short-term thing, not a serious relationship..." and the Thinapped vSphere Client is one of the best flings available. If you have never used the Thinapped vSphere Client, then all you need to know is that it is a fully functioning vSphere Client delivered in a single executable file. And now version 5.0 U1 is out, which means I can start enjoying this fling in my vSphere 5 environments.
The Thinapped vSphere Client proves extremely useful for many of the users I work with who don't (or can't) install software on their machines. At 92MB in size, it can also be a much faster download than accessing the 350MB installer from vCenter Server. I also find it very useful on servers (think Windows backup servers) where I don't necessarily want to install any more software than I absolutely have to.
If you haven't checked out the Thinapped vSphere Client, then now might be a good time!