My company uses Perforce as its source control system. It's a great tool.
Here are a couple of simple shortcuts which I have found save me a lot of time:
CTRL+C: highlight an item in your source tree, and the path to the file in the souce depot will be copied to the clipboard, i.e. : //Depot/Project/Docs/Use Cases.doc
This makes it really easy to point someone to a file you've been working on; just select the file, copy the path and email it to them.
CTRL+V: When you are emailed a path in the fashion described above, copy that location into the clipboard, switch to Perforce, and hit CTRL+V. Perforce will auto locate that item in the tree. Kudos to John, who discovered this one.