for builds locking the IDE I usually peek at my inbox, unless I have a second IDE were I'm working on something else. For build running remotely it depends, if the build takes 10-20 mins (in my ideal projects) I just keep working. In other worse projects were it can take 1-2 hours, I tend to run them at the end of the day so I don't have to think about context switching too much.
Generally I try to do non-random things -- like work on other aspects of the project, you know, in parallel.
That is, if I care about the project at least. When management goes out of its way to make me not care? Then I check HN and WP, just like you.