Ok, here's little key board short cut that I use....
when replying to a group e-mail and if you don't want
the prior mail text to show in your message.
after you hit the reply button your cursor will be setting
in the text body of the message, just press Ctrl-A
which will select all the post text, then hit the delete key.
and your ready to to type.
Want another one?
When you are browsing the Internet and you want to open another
page to search for something or what ever, like when your on e-bay
and you don't want to loose the page, but need to look up the item
your looking at....just hit Ctrl-N