I've been using SnagIt for years and absolutely love it.  Recently, I needed to grab a picture of menus but also needed to apply some effects to the unimportant areas so as to draw more attention to the menus themselves.  I stumbled a bit with the freehand selection tool, largely because I can't draw a straight line for diddly.  The rectangular selector was *so* close to what I wanted but it kept bringing in parts of the image that I didn't want to highlight.  Out of curiosity, I tried the old Shift trick and it worked exactly like I'd hoped!

What is the Shift Trick?

• Use the Selection tool of your choice and make the first selection
• Hold Shift and make another selection such that it partially overlaps with the first. 
• SnagIt will merge the two selections
• repeat as needed

This allows for some really odd selection shapes but is quite handy when you need to outline complex areas.  In this picture, I was able to select just the menus and then dim and blur the background.

(and for the record, yes, I could have applied the Torn Edge effect to the selected area which resulted in torn edges on each of the menus.  Interesting, but lost clarity)

Just for fun, I wanted to see what I could do with this - pretty neat, actually.