"With InDesign, you're buying a platform, but with all the plug-ins, you've just doubled or tripled its capabilities and your investment," said Niemann-Ross, the evangelist for Adobe System Inc.'s Creative Professional Unit, which includes InDesign.

InDesign is page layout software that is integrated with other Adobe applications (part of the Creative Suite) and offers production workflows.

"InDesign was built around being able to extend it with plug-ins," Niemann-Ross said. "Developers have been a part of the philosophy of InDesign since the beginning."

From the start, Adobe has shared a great deal of the inner-working APIs of InDesign with developers in the hopes that great things would come of that.

Niemann-Ross says it's been an incredible journey.

"It's been really interesting to see what they'll do. If you want innovation to work, you just have to open your doors."

Chris Jones, director of product development for Triple Triangle, a company that produces plug-ins for InDesign that address the needs of the advertising vertical market, calls this platform extraordinary in its openness.

"I've worked in a lot of platforms and none have been this extraordinary. You can do amazing things because you have unparalleled options to customize this," said Jones, who formerly worked at Adobe and on the InDesign product.

The latest trends that Niemann-Ross, who works with the developers every day, has seen have been around newspapers and catalog publishing.

"Newspapers started off wanting to do their own thing and then maybe add on a platform afterward to more specific tasks," Niemann-Ross said. "Now they're realizing that they're better off just buying the platform because with all the plug-ins, they have unlimited flexibility with the systems. That's what they were after to start with, and now InDesign can do that."

Companies such as pcsdotNet provide plug-ins to help newspapers move from their old publishing workflow to an InDesign-based system with a plug-in called Adapt.

There are numerous publishing tool plug-ins that expand the abilities of InDesign, from handling color and transparencies to its workflow processes.

Softcare has created an entire editorial system, the K4 Publishing System, for InDesign CS and Adobe InCopy CS, which is designed to organize the work of graphic designers and editors, as well as to control the production process. It has multilevel security controls to support entire publishing operations.

"Different vertical markets have different and very specific needs," Jones said. "Plug-ins really are about addressing those specific needs in the workflow process."

His company sells Tick Tock, a way to track how much time a free-lancer or design department has spent in an InDesign document; Spec Cubed, a way to analyze the contents, attributes of an InDesign document; Color Spec Cubed, which visually annotates InDesign documents with color, font and placed graphic usage information; and Slug Cubed, which simplifies the design and maintenance of slugs, page elements that contain standardized information about a document's contents and status.

The other big winners are those making plug-ins for catalog publishing, according to Niemann-Ross.

"With the plug-ins available, you can turn yourself into a catalog or phone book publisher, something that's not that easy to do."

Many of the plug-ins available for this arena are centered around maintaining and tracking workflow processes with databases.

With many catalogs now needing specific versions for specific areas or for the Web, it's become a big business in plug-ins to help them do that, according to Niemann-Ross.

"InDesign doesn't understand in that depth of detail, so that's why we need developers, to address these very specific needs."

Plug-ins go from the mundane, such as Virginia Systems plug-ins (Sonar Bookends products), which address advanced indexing options, to the innovative.

A company called Knowbody, run by Søren Rehné, has come up with a plug-in that allows you to control Apple's iTunes through InDesign, called TuneIt.

According to the Web site: "A lot of people who work with InDesign often listen to iTunes music while working. Up till now, the only way to switch between playlists and tracks has been to change programs. But now by using TuneIT you are able to control iTunes directly from InDesign." It also has its own tool palette.

"It seems like, 'Who would think of that?' but people love this thing," Niemann-Ross said of TuneIt. "I guess there's a huge mapping between music and designers, and this taps into that market."

There are numerous sites that have lists of plug-ins for InDesign (among other programs).