The preloader is perhaps the most often overlooked element of most Flash projects. In its most basic form, the preloader consists of a moving bar or changing percentage that indicates the load time of a Flash file. Preloaders are especially important for large files and/or video for which the user may have to wait some time before the Flash file is ready.
There are a number of tutorials on the web for creating preloaders, including an incredibly detailed rundown from senocular.com, a preloader that is itself detailed can be found at LukaMaras.com, and a preloader that displays load progress from 10,000 words favorite kirupa.com.
And they don’t have to be bars either. They can be games, animated timelines, fill an object like the one at Game Boy micro, or circular like the one found at Mohammad Rahimi. Detailed instructions on how to create a circle preloader can be found here.
If your Flash project is related to health or medicine, this tutorial on how to create an EKG-like preloader will come in handy. An exhaustive list of tutorials can be found at VCL Components. Once a preloader is developed it can be used repeatedly by copying and pasting the movie clip into a new or existing Flash file and tweaking a couple of parameters.
If you need a little inspiration, Smashing Magazine has a great gallery of Flash preloaders as does Flash Speaks Actionscript. If you’re not quite ready to code your own preloaders, sites like istockphoto have many stock preloaders that run the gamut from easy and basic to extraordinary and unusual like this pencil preloader, this vertical liquid loader and one that resembles a speedometer.
For an inspiring gallery of Flash preloaders, check out Pretty Loaded