Which ones do you use? What do you see as benefits/flaws to them?

Everyone (mostly) know how to use images. But are there others you use or have seen others use?
Or in the case of images, how much work do you put into such?

To give a couple of examples (one someone else's, one ours):
[hider=Minecraft]
We saw a mention elsewhere of someone using Minecraft as a visual aid for their RP. 
[b]Perks:[/b]
Collaborative construction - Everyone in the RP can help build it
Interactive - You can literally walk around the map (or whatever it is)

[b]Flaws:[/b]
Severely oversized pixels
No option for non-right angles
Few materials to work with
Requires ownership of minecraft to access
Heavy on computer memory due to minecraft's sub-optimal code structure
[/hider]

[hider=Sketchup]
This is the tool we use ourselves. It too has perks and flaws.
[b]Perks:[/b]
You can have virtually any level of precision, all depending on scale. From the nanometer precision to objects countless kilometers in size.
No limit on angles.
Only imagination and time sets the limit on what you make.
New materials can be made at will
Free - you don't have to spend money if you don't want to.

[b]Flaws:[/b]
Not interactive. Sure, you can upload model for others to download, but its not too practical.
Cooperative editing not possible. Not without everyone working on it uploading after each change, which is not exactly practical
Somewhat steep learning curve, but not as steep as some programs
No rendering (without extra tools, of course)

[/hider]