The first, (Welcome PM) simply sends a PM welcoming all new users to the board which should help new users get settled faster and also show them some of the most important pieces of information.
The Quick Reply Panel:
The Quick Reply Panel is shown on every page and allows you to make a reply to the post without loading a separate page, which should make it a lot easier to reply in a logical fashion to the last posts (as they will be directly above your reply and not reversed underneath the reply pane).
You can still use all the BBcodes as you can in the normal reply pane too.
If there is a piece of text you want to quote, you can still do that too!- just select it by dragging over the text and then clicking on "Quote" underneath the user's name. This will automatically put the selected text into quote BBCode in the Quick Reply.

"Urgh, I hate this, how can I turn it off?!"
Don't worry! It's really easy to turn on and off:
- Click on the "User Control Panel" link at the very top of the page.
- Click on the "Board Preferences" tab.
- Click on "Edit Display Options" (on the left).
- Turn the option "Display quick reply panel at topic view:" to "No".
- Click on the "Submit" button.
That's it! If you want to turn it on again at a later date, just do the same thing but set the option back to "Yes" instead of "No".
Special Thanks to Nelsaidi for helping fix a problem with the QR box!