To post pictures you have to download them on to a image hosting site (I use Photobucket), and then copy the URL of the image in between what comes up when you press the image button (the painting underneath the bold button).
Anyway, here are a few from me (from No Limits- the superior roller coaster designing software ).
I'm sure others are much better, but these are the best I can do (in 2 minutes).
A few images from my old RCT3 park. These are about 5.5 years old from when the range of custom scenery was quite limited and the CTR's were non-existent. It was a monster of a park and took my computer 20minutes to load up, and then I couldn't really do anything except take the odd screenshot. I still have the same computer now and daren't even try and load it again.