I've kinda been hoarding them till I had some decent ones to show.
I find I have really bad luck with one hue glitch and the random hue circle.
Mountain Scape 1
http://img521.imageshack.us/img521/9444/mountainpic008vt1.png
http://img521.imageshack.us/img521/6536/mountainpic0072cz7.png
Mountain Scape 2
this one is rather large
http://img341.imageshack.us/img341/152/mountainpic0093perfectepe8.png
i had to fix the above image from this
http://img248.imageshack.us/img248/2671/87820160tt0.png
Random
Lake
http://img248.imageshack.us/img248/8250/laketest001gg1.png
Canyon/Mountain 1
http://img521.imageshack.us/img521/1769/canyon002xi1.png
Canyon/Mountain 2
http://img521.imageshack.us/img521/8997/canyonpic001qs8.png
My current project is huge,its been rendering for a couple days. But thats because I have a lot of grass, and the render itself is large. I think the grass itself is only on medium though. Oh well, I think it looks pretty good so far. Anyway, critiscism and tips are really appreciated.
You should raise the samples in the quality tab of the atmosphere to reduce the grain.
I agree with Volker. Most of your images look pretty cool and yet a few lack that extra special something I find so illusive in my own, which has something to do with what Volker mentioned about leaving just enough for the imagination to find something interesting.