I have been writing riffs in 5/4, 6/4, 7/4 for years and thought I had a pretty decent knowledge about odd time signatures.
Then I went to one of IA Eklundh's Freak Guitar Camp's and realised I didn't know anything. NOTHING! I was exposed to stuff that makes Rush songs look like child's play.
His knowledge in konnakol that is taught extensively at these camp's made me realise that there's a whole world of rhythmic complexities that I haven't scratched the surface of.
Here's an example of some of his stuff that he teaches (check especially out the part from 3:45 onwards that sounds as it's accelerating, but there's actually an underlying beat(!) ):
[youtube]https://youtu.be/ZUdfJQtsOj0[/youtube]
Here's another example of his where he explains and breaks down the rhythms used ...
[youtube]https://youtu.be/1ggqyh_X7S8[/youtube]