the harmonic major

Since I just discussed the major key a bit here's a plug for a related mode: the harmonic major. Compared to the major scale it's construction is:
1 2 3 4 5 b6 7
the b6 being the only difference from the major scale. C harmonic major looks like this:

At first glance this might seem like a mode of F melodic minor, but the melodic minor doesn't have a #4, so this is a different animal altogether. ^{FN 1}

The name comes from the fact that the upper tetrachord (4 notes) of this scale is the same as that of a harmonic minor with the same root. In this particular case: G Ab B C. The bottom tetrachord is the same as a major scale, hence "harmonic major".^{FN 2}

That's just one application. Others are taking triads or other harmonic structures from the scale and building tunes/pieces from them, and exploiting those new nuances of mood.

And another plug here: for names (and structures) of many, many modes visit this site.
----------

1. Though we could insist that a melodic minor sharp-4 is the parent scale and that this is consequently a derived mode.

2. Actually analysing with respect to tetrachords is a topic in its own right. It has the advantage of being able to quickly isolate where differences occur between modes. Another meaningful example is the melodic minor itself: it's often called an Ionian flat-3. This because the upper tetrachord is the same as a major (ionian) scale, and when the bottom two tetrachords are compared the differnce found is that the melodica minor has that b3.