I use a simple PowerPoint 2007 "glow" to get a graffiti-style effect. In the image below, I selected the "Boopee" font (standard in PowerPoint 2007) to which I applied a red glow and a gradient text fill (bright red, with a darker red). The background image was purchased on iStockPhoto. Let me know in the comments if you need more detailed instructions.

Be sure to avoid setting yourself up for disaster when using non-standard fonts in a PowerPoint presentation.