Take a listen to these scales. You hear them all the time in a variety of music in one form or another - for example, a dreamy moment (whole tone) often played by a harp, or a suspenseful chord played as the villain in a drama attempts some dastardly deed (diminished arpeggio). Just knowing a bit about these scales and how to play them on your instrument will really add to your "tool kit" of skills.
(Hint: click the "Noteflight" logo to view the whole page and text - it's a bit crunched in this view. You can also click the Play button and hear what these scales sound like!)
Note that both of these scale types (whole tone and diminished) are known as "symmetric" scales - in other words, each note is equidistant to the next. The result is a unique sound. Any note can be the starting point for a new scale, since there's no half-step interval to provide the sense of "leading tone" weight.
When you listen to music, you'll recognize these elements (whole tone sounds and/or diminished scales) as the funcitonal devices they often are. In classical music, composers often used the diminished scale/chord to provide a sense of suspense and/or harmonic ambiguity. Hence, they are perfect for development sections and/or as a means of transitioning to a new key center. In Jazz (especially), the diminished scale is closely related to a "dominiant"chord . In fact any diminished scale is really a dominant 7 with a flat 9. For example, if you play a D7(b9) chord (piano/guitar), a C diminished scale will contain all those notes. Sounds a bit complex, but only at first. Your ear knows all this already, it's just a matter of putting a name on some of these things. Happy playing!