Plug-ins are a great way to extend the functionality of Photoshop, adding fun filters and fresh features to the application. Although most plug-ins are modestly priced, a number of cool plug-ins are available for free. Here is a round-up of some of the best freeware plug-ins currently available for Photoshop CS3, CS4, and CS5, and, in some cases, Photoshop Elements 8 and 9.

You can install plug-ins by dragging the plug-in file into the application’s plug-in folder, found at /Applications/Adobe Photoshop/Plug-ins. Many plug-ins now include their own installer, however, and some newer plug-ins must be installed via the Adobe Extension Manager. Once you have installed a plug-in, you can usually find it under Photoshop’s Filter menu, though you access some plug-ins via Window > Extensions.

PhotoTools 2.5.4 Free
PhotoTools 2.5.4 Free, from onOne Software, is a fine collection of photographic filters, including cross-process, cyanotype, sepia toner, and vintage. The plug-in app commands the full screen, placing before and after previews side by side (www.ononesoftware.com).

Photoshop Edge FX 2.2
Sebastien Piconnier’s Photoshop Edge FX 2.2 works with Photoshop CS4 and CS5, and lets you enhance your photos with an arty graphic border. You start by choosing from more than 60 preset borders, then you resize and reposition them. You can apply layer styles such as Glow and Drop Shadow. You apply the borders as masks, to preserve your original photo (www.myphotoshopeffects.com).

Dreamy Photo 
Auto FX Software’s Dreamy Photo allows you to infuse your images with a soft, dream-like quality. The program includes presets for soft-glow, blurry-zoom, and trippy rotational-blur effects. The plug-in is hampered by an awkward interface, but the resulting images are nonetheless quite compelling. This plug-in works with Elements but is not yet compatible with CS5 (www.autofx.com).

Pixel Bender 
Adobe’s Pixel Bender is an interesting (and, for now, experimental) add-on to Photoshop CS4 and CS5 that uses your computer’s graphics processor to literally bend pixels. The included filters are a bit hit-and-miss, although you’ll certainly be impressed by OilPaint. You can download additional Pixel Bender filters from Adobe Exchange (labs.adobe.com).

PhotoFrame 4.5.2 Free 
PhotoFrame 4.5.2 Free, another plug-in from onOne Software, lets you apply graphic frames – such as film reel, Polaroid, and water colour – to your photos. You can combine borders and textures to create unique effects; and borders are applied as a layer, which preserves your original photo. This plug-in is also compatible with Elements (www.ononesoftware.com).