I prefer "Mount.app". That one displays an error message if the DMG file is broken. FlashMount doesn't do that.

So DMG is a technically superior format. Fair enough. I still want to expand them into regular folders and delete the original DMG file automatically. :)

@Brian: I vastly prefer when disk images are used, actually.
Think about it. If you have, for example, a .zip file, you need to either extract the whole thing, effectively tripling the space used by the same data (or more or less, depending on compression), or use a separate app to view and extract an individual file... but you can't ACTUALLY view them, or execute them, just see the filenames.
In a DMG, mounting it doesn't take more space. You can see, execute, and preview all the files, again without using more space (yes, there are a few limitations, but they're rare). You can extract the files you want, where you want, without wasting space.
On top of that, it comes with built-in MD5 checking of the data, so you know immediately if you have an accurate download, and it's WAY faster to access the data in the image than in a zip (try it: re-mount a 500+MB image. Re-extract a 500MB zip file).
I use DMGs for archiving images, because I can see thumbnails, show them off without extracting, and preview large numbers of them without extracting several-gigabyte archive files. It's basically not possible to do with a zip what you can do with a DMG.

Quite lovely. What I'd really like is to be able to extra DMGs into folders (with an option to delete the DMG afterward). Why do people insist on distributing software on disk image to begin with? So they can have pretty background pictures? Puh-lease.

since i installed this its been great in helping me quicly open the freware in dmg's for my computers. a great little app to use instead of osx's disk utility, i recommend it to anyone who uses osx.

I keep some large apps like games (Unreal 2004) in compressed DMGs to save hard drive space (up to 60%). Mounting large DMG files with OS X's built-in tools can take a good long time, so this comes in very handy.