A neat property of dominant chords is something called
flat fifth substition. The idea is, the main thing that defines the sound of a dominant seventh is the
tritone between the third and the flat seven. By scaling an entire dominant seventh chord up a tritone, those two notes stay the same, and the added tension from changing the root and fifth to notes that probably aren't in the key being played can easily be resolved.
For example: Consider a simple ii-V-I progression: Dm7 -> G7 -> C. Spelled out, we have (D F A C) -> (G B D F) -> (C E G). By substituting the G7 for a C#7, the B and F retain their position in the transition. We're left with G# and C#, which seem like they would sound out of place. But the Dm7 has the notes D and A, and the C has the notes C and G, so the new progression now merely has two short chromatic lines: A->G#->G and D->C#->C (don't give me shit about parallel fifths... if you have a problem with them, then play the chromatic notes in different octaves or something).
This works well with all dominant chords (ninths, thirteenths, whatever), and you can just come up with some pretty neat changes just playing arbitrarily-rooted dominants. If you syncopate these, non-musical bystanders will think that you're a skilled jazz musician.
If you happen to play the guitar, here are the CAGED forms of the dominant seventh on the guitar neck:
------------1---0----2---
---1----2---0---0----1---
---3----1---0---1----2---
---2----2---0---0----0---
---3----0-------2--------
----------------0--------
C7 A7 G7 E7 D7
By sliding those shapes around and using
this handy information, you can form any
inversion of a dominant seventh imaginable.