More than eight in 10 Internet users also do some offline activity while online, according to Burst Media. Burst found that nearly three out of five Internet users watched television while online.

"TV and the Internet have long been multitasking buddies," said Debra
Aho Williamson, senior analyst at eMarketer. "It makes sense to create
ad messages that resonate across media."

Multitasking* Activities of US Adult Home Internet Users, October 2007 (% of respondents)

The second most common offline activity for online multitaskers was
job-related activities (33.0%), followed by reading a book (31.1%), a
magazine or newspaper (29.7%) and talking on a mobile phone (23.6%).

"Keep in mind that many of these activities are not representative
of true multitasking," Ms. Williamson said. "It’s one thing to go
online with the radio playing in the background, but it’s all but
impossible to read text on a Web page and in a newspaper at the same
time. Consumers are switching focus, rather than multitasking."

"Still, anytime your attention is divided, your ability to recall and comprehend ad messages is impacted."

The Web is not the only medium to which consumers are giving divided
attention. Music listeners and instant messagers were even more likely
than computer users to be juggling media consumption, according to a Bridge Ratings study.

Percent of Time Spent Using Select Media that Is Shared with Simultaneous Usage of Other Media among US Consumers Ages 14-27, February 2006 & February 2007

Via eMarketer