Mac OS X 10.5 introduced a new feature that warned users when they first opened a file downloaded from the Internet. It's a protection mechanism to prevent users from opening potentially harmful files. It's also extremely annoying for users who download many files from known trustworthy. Thanks to a script from Creative Bits, disabling this feature just became a whole lot easier.
When this download warning first debuted, Macworld detailed a few terminal commands to disable this feature. You could either disable it permanently which removed all protection from accidentally downloaded files or disable it on a case-by-case basis. Running the command on demand lets you decide when you want to disable this protection, but you have to remember the command each time you wanted to turn it off. Having to look up the command was almost inconvenient as responding to the warning dialog in the first place.
To make it easier, Ivan from Creative Bits has created an Automator script that you can place in your Dock. Every time you need to download a bunch of files, you can simply click this script to disable the warning. You can download the script from Creative Bits website to try it yourself. It should work on Mac OS X 10.6 and 10.7 Lion.