Portable recorders like the Roland R-05 or Blue Microphone Mikey can be used to record people on the go that you may bump into. You never know who you'll meet when out and about or at a convention. Celebrities, authorities on your subject or a listener to your radio show/podcast. Grab an interview or sound bites with them to use as content for your show or clips for radio jingles.

Roland R-05: http://jngl.es/r05
Blue Microphone Mikey: http://jngl.es/mikey