ICQ in April began providing partners with access to the software's application programming interfaces, or APIs, so they could develop programs that run inside the IM client. The ICQ unit plans to offer an open API license to the public soon, according to a notice on its Web site.
Applications created under the program are known as ICQ Xtraz, and now include video chat, several games and a sketching tool that lets users create custom avatars.
The video chat application, announced Monday, works only with ICQ 4.0 on PCs running Microsoft's Windows XP operating system.
Xtraz are downloaded and installed much like browser plug-ins. Upcoming Xtraz include an ICQmail application.
In the late 1990s, the ICQ tool helped establish instant messaging as a major new communications technology, but its influence has waned since AOL acquired its maker, Mirabilis, for $287 million in 1998. ICQ recently had about 20 million audited monthly users, mostly in Europe, Asia and South America. AOL's IM program, AIM, by contrast, counts about 36 million monthly users, mostly in the United States.
By publishing open APIs for developers, the ICQ division hopes to turn its instant messenger into an application platform--a risky path that was also attempted and later abandoned by AOL's Nullsoft division with its Winamp multimedia player.
ICQ in the past has drawn criticism for becoming too bloated, prompting the company to release a stripped-down version of ICQ known as ICQ Lite.
A representative for the Israel-based ICQ unit was not immediately available for comment.
AOL has also begun offering software development kits for building ICQ chat and presence features into third-party applications.
In September, Macromedia announced the release of a new developer version of Central, the company's project to create Flash applications that run outside a Web browser. The new version 1.5 of Central includes a software development kit for connecting Central to AOL instant messenger and ICQ.
Macromedia announced its partnership with AOL last year, a move that was seen as critical for boosting Central's appeal. Central has yet to generate significant interest among developers, however, who have expressed concerns about usefulness and licensing terms.
CNET News.com's David Becker contributed to this report.