[private]This one is very short and sweet , i was working on a few files and this was a big file with numerous illustrations which i needed to convert to JPG and well as PNG . And while searching through google i found this little handy dandy script provided by HicksDesign .
All you have to do is place all your graphics in separate layers and then just run the script , the png is cropped to the artboard and saved through illustrator to the folder of your choice. Find it HERE
And if you are looking for a way to do the same in photoshop then fear not , Photoshop CS4 already has a built in script for this . But what about someone who has CS3? well here is a very useful link for Photoshop CS3 exporting to layers PNGs Seekers . Find it here!.