This is actually a Windows7 and Vista tip with an Outlook angle. It works in older versions of Windows as well, but only with the QuickLaunch toolbar. (Outlook 2010 uses Win7's jump list capability for shortcuts for new items. )
A user asked this question:
I'd like to have a shortcut in my system tray or sidebar in Win 7 so I can create a new appointment without having to open Outlook 2007. Is this possible?
I'll address the "without having to open Outlook" part first. Yes, you can have shortcuts to create new items but when you use them, Outlook will open in a hidden state. If you use an account that doesn't require you to log on, you probably won't notice it. But if you use an Exchange account that requires a password to access or password protect your PST file, you will need to enter the account information or password to use a shortcut while Outlook is closed.
To run a shortcut in the system tray or sidebar you need to use a utility (or a sidebar gadget). One tray utility that offers shortcuts for new items is Knockout. It works on Win7 and with all versions of Outlook, including Outlook 2010 x64.
Generally speaking (because they use no resources) its better to pin a shortcut on the Start menu, on Win7's Taskbar, or add a shortcut to the Quick launch toolbar. (Sidebar gadgets that access Outlook data are known to cause issues with Outlook not closing properly. )
Pinned items are just shortcuts in C:\Users\
You can easily make your own shortcuts for new items using the following command line:
"C:\Program Files\Microsoft Office\Office12\OUTLOOK.EXE" /c IPM.APPOINTMENT
Change the path to Outlook to match your version and if you want to open other forms, change IPM form to any valid published form.
Creates shortcuts for new Outlook item in the Quick launch folder for you. In Win7 and Vista, the quick launch shortcuts are at C:\Users\