Azureus is still going strong as a Mac P2P client, and it's one of the few that allows you to monitor downloads using a simple widget.
The Azureus Dashboard Widget can be used for monitoring downloads remotely or those on your machine. Even better, you can have multiple instances open, so you can have as many downloads going as your Mac can handle if you want.
You will, of course, need Azureus running at the same time as using it because this widget is only the front end. Unfortunately, it also requires the 'XML over HTTP plug-in' installed beforehand.
The advantage of using this widget is that it avoids having to use the sluggish Java interface of Azureus but it doesn't avoid the problem of having to run Azureus anyway. It's also obviously only a monitoring tool - it's no good for those that want to administer the client.
Azureus Dashboard Widget is definitely worth trying for those who often monitor Azureus remotely or don't want to use its slow interface.