People routinely use their computers to share baby photos, corny jokes and hot music files, but an invention by Carnegie Mellon University computer science students is helping users share something more personal: their emotions.

"MoodJam" is a software application that helps people express their moods in words and, strikingly, in bands of color. This creates a colorful and often artistic daily record, displayed either on MoodJam's Web site, www.moodjam.org, or on an individual's homepage.

Ian Li, a Ph.D. student in the School of Computer Science's Human-Computer Interaction Institute (HCII), led the development of MoodJam. He envisioned it as a "visual diary," a means of using the computer for self-reflection. But with more than 2,000 people now using MoodJam, it is proving popular as a way to share moods within workgroups, circles of friends and even far-flung family members.

"The sharing aspect does make it more attractive," said Li, who launched the MoodJam Web site last November along with HCII research associate Aubrey Shick and fellow Ph.D. students Karen Tang and Scott Davidoff. "To get insights into your own moods, you have to record for at least a week. But the social benefits from sharing are immediate."

A "gadget" version of MoodJam, which can be installed on an individual's homepage, won in two categories of the inaugural Google Gadget Awards, a student competition sponsored by Google Inc. Late last year, Gina Pell, CEO and founder of Splendora.com, judged MoodJam to be the "prettiest gadget," while Rob "Commander Taco" Malda, founder of Slashdot.com, judged it the "gadget most likely to help you get a date."

Li can't testify to MoodJam's date-getting powers and can only speculate on why Malda selected it. "I guess the idea is if you're more sensitive to your emotions, you're more attractive to the opposite sex," he said.

The colors or combinations of colors used to express moods are not prescribed: each user chooses colors that seem appropriate. Likewise, the words used to describe moods - accessed by mousing over the color bars - are individualized, resulting in such eccentricities as "caffeinated,"just kinda eh" and "fantabulously magical."

"A friend in Seattle just IM'ed (instant messaged) me. 'Ha, ha - your mood is hilarious today,'" said Shick, who "moodjams" with friends across the country. It's also proven useful to her mother, who lives near Somerset, Pa. "She likes that she can see how I'm doing without bothering me," Shick said.

Though updating MoodJam throughout the day might be an imposition to some, it becomes second nature for people such as Shick, for whom online socializing is the norm. "I'm on the computer all day long - 15 or more hours a day," she explained. "It's no effort to keep on logging."

MoodJam may or may not prove to have research applications. One of Li's faculty advisors, Assistant Professor of Human-Computer Interaction Anind Dey, said the software is "extremely exploratory," but poses interesting questions about how mood-sharing affects the dynamics of work groups. It also provides a tool for recording moods and emotions, which could be used to study how moods converge and diverge within work, family and friendship groups.

Li's interest in developing a tool for logging emotions is related to a larger trend in computer research - the use of computers to provide personal feedback. Li's main research area, for instance, examines how computers can gather and analyze information about physical activity, health and diet.

"There's a lot of information out there about health and physical activity, but people don't understand how to interpret it for themselves," Dey explained. Other researchers are exploring additional ways that computers might provide "personal data mining," such as analyzing daily computer work to produce suggestions for improving productivity. One project under way at HCII analyzes personal driving styles and preferences to produce personalized route planning.

For more on the Google Gadget Awards, see www.google.com/intl/en/events/gadgetawards/winners.html.