ONTHESCREEN NAME  Tiger (Mac OS X v10.4) is where and why Indicator(s) was conceived.

It is very suitable for the Dock in even Mac OS X v10.1 and beyond.

Thanks for the comments!

Even stated on the website, which is in itself in a more developing process, the application is behaving in the intended manner. In that it does not stay open, because it does not have to. (The attributes for creating a blank script with /Applications/AppleScript/Script Editor, "Read-Only" & not to "Stay Open", are as such and "normal") Plus the concept alone is enough for people to actually do this all the time; organize/efficiently use what they need to, all the time.

And in order to be stable, easy and fun (appropriate and appealing) the simplest process was used and here we are, having to discuss it.

It very may be possible and soon that a Leopard version of Indicator(s) may be on the horizon. This time actually taking up memory and staying open!

Other applications are in the works. Please develop and evolve with us!

Note: The developer actually replied to reviews on the same day as the release. However, due to some difficulty, the post did not show up.

Again, thank you, and please read all applicable information before posting! Thank you!  
(Version 1.0)

DEREKJAB  Only applications can live on the left side of the dock. If you're paranoid, you can simply had a spacer to the dock using the terminal commands:

defaults write com.apple.dock persistent-apps -array-add '{tile-data={}; tile-type="spacer-tile";}'

killAll Dock

Spaces are, to my mind, much more elegant anyway.

If you're not comfortable with the terminal, get Tinker Tool or the Secrets PreferencePane.  
(Version 1.0)

ZZAMBONI  There's a built-in way to add blank separators to the dock. You can see it here: http://zzamboni.org/brt/2007/11/21/real-separators-for-the-leopard-dock/

These are true separators, not empty scripts or apps - however they are always blank, no way (that I know) of getting them to show an image.  
(Version 1.0)

SHANE C SMITH  Is it me or are these just icons that have no application attached to them? Ummm, when you download them they appear to be applications but I'm a little weary to double click them since I have no idea what they do?  
(Version 1.0)