Let's start out with a list.

• First and foremost, along with #1 on the Google search results, the original PNG Fix from Bob Osola.
• Bob references a different solution by Drew McLellans known as SuperSleight which I think originally comes from YoungPup's Sleight.
• This one from Unit Interactive claims to fix interativity problems (with links). It's called Unit PNG Fix. Apparently it's all the rave.
• Here's a PNG Fix which uses Flash and SWFObject known as PNGPong by psyrendust.
• Here is TwinHelix's CSS behavior solution.
• I haven't taken the time yet to compare this behavior from Erik Arvidsson to TwinHelix's version, but here's a link for you to decide.
• Here is yet another behavior fix from Dave Woods.
• Another behavior fix from vibemanslim.
• This one from TJK Design has received a few good reviews.
• KomodoMedia did not like TJKDesign's version, so came up with their own.
• Project Atomic claims to have a better IE PNG fix... so does greyHats.
• Daltonlp's method immediately points you to bjorkoy's, which apparently doesn't work.
• Since Perishable Press's uses "leet speak", it must be the best. It's called CSS Hackz Series: PNG Fix for Internet Explorer.
• Check this bit out from Pathfinder Development.
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• This fix is specific to Drupal. A PNG Fix is also included in White Jazz's Theme.
• This fix is specific to Yoothemes for Joomla.
• This fix is specific to Joomla. This one is also for Joomla known as Ultimate PNG Fix.
• These fixes are specific to Wordpress: Taha Paksu | Vril's.
• This fix is specific to Mootools.
• Looking for one to work specifically with jQuery? Well, here are a few: jquery.pngfix | jquery.ifixpng (and v2) | Campbell Digital Soup | Jeffrey Olchovy.
• This is a PHP specific fix by Koivi.
• Here's a PNG Fix Control for ASP.NET by Stefan Sedich.
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• A straight forward CSS Hack solution is applying a filter to an HTML element. Here are the details.
• A List Apart has an excellent explanation here.

Ok, that should be enough to get started. There will be plenty more developments as well as the opportunity to submit/correct the current entries. Thanks for visiting.