Fake Transparency
The most standard type of transparency is wanting to have graphical text (usually some sort of header or page title) have the appearance of floating on the page. Believe it or not, the easiest way of achieving this effect is to not use transparency at all! Simple background matching is the most effective way of achieving seamless effects.

At the most basic level, this involves matching the background of your image to the background of the page on a single-color level. In Figure 1, we have an image floating on the white background of the page. The drop shadow gives the illusion of distance from the background, a pleasing visual effect. With simple page colors like black and white, this is simple to achieve—choose your HTML page background to match your photo backdrops.

Figure 1: Simple background matching.

In the case of photographs or other high-color images (anything greater than 256 colors), this method is ideal because it allows you to maintain the quality of your image and use high-color effects like Ulead frames and filters. The image below would look very bad in 256 colors!

Figure 2: More perfectly faked transparency!

Tip: Be careful to not compress your JPEG image too much, or the artifacts will show up and ruin the floating effect. Compression levels below 60% will often have this effect, and it's most noticeable on backgrounds other than white and black.