The company I work for has a computer with internet connection, in the lunchroom, so it's available for all employees to use.

(Small company though, only about 35 people at our location).
I sometimes sign online 3 times a day; 10:30pm which is my first 15 minute break; 12:30pm which is my half-hour lunch; and around 2pm which is my afternoon break. I only work until 3:30pm, so I pretty much am able to get online every hour and a half, if I want to.
Lately, I seem to just read a book, or chat on my cell phone during lunch.
I'd NEVER sign online from my desk, during actual work time. I personally consider that to be "stealing from one's employer".
EDITED TO ADD: My feelings on "stealing" from your employer are in relation to only those companies who DO NOT want their employees to be online doing personal business/message boards, etc, during their work day (not during breaks or lunch).