Sure there is: just click all boxes
If you want to switch often, just create another account, and use it in a different browser with a large ignore list. I ignore many boards on LoyceMobile, while I see everything on this account.

You can select boards like this: https://bitcointalk.org/index.php?action=recent;boards=1,77,6,37,4;patrol
I'm not sure who taught me that, but I keep this one bookmarked.
Update: It was o_e_l_e_o.