So, here's my 30 seconds worth of advice on PowerPoint:
Use PowerPoint as a visual channel of communication to back up what you are saying. Don't use bullet points, don't read from your slide and don't turn your back to your audience. If you have more than one sentence on a slide, it's too much. You can give your audience a handout after you present, but while you're speaking, they should focus on you. Sum up your main points, express that with a full-screen picture and type a simple caption.
That's about all I can say in 30 seconds. What advice would you give in a half-minute? For PowerPoint? For your area of expertise?