Brevity is a powerful tool.  It’s rare (though not completely unheard of) to hear complaints that a presentation was too short.  People appreciate your respecting their time and will have a strong impression of what you say if you do it economically.

Why do meetings always have to be an hour long?  Try scheduling something for 20 minutes, or 45 minutes.  People will often be surprised by your unusual timing and it will make a favorable impression on them because they’ll see that you’re making an effort to do something different and respect their time.