I have found a solution! It's called Snap Links. It allows you to open multiple links at once, and I loooove it. I even put off upgrading to Firefox 3 until they had a compatible version.
Snap Links only works on Firefox, which I'm sure all of you very smart clever people already use. If not, you can download it here. Then you can download and install Snap Links here. Once installed, all you have to do is right click (keep holding the button down) and drag the box until it selects the links you want to open.
Let go of the button and the links you've selected will pop up in new tabs.
Geez, I have a lotta bookmarks in my quick-link bar... but look at the opened tabs! Those are the links that were selected in the previous screen shot.
In addition to using it for Mr Linky posts, I also like to use it when I'm doing a random Google search and want to check out several of the hits at once. It's also good for "Link Roundup" posts. Maybe I'm just really lazy but I hate clicking and going back and forth between tabs and windows when I don't have to!
I don't recommend clicking on all 300 links at once because your computer will likely have an aneurysm and then you will be sad. 10-15 links seems to be a pretty good number, and it also breaks the list down into bite size pieces! After you've read your snapped links then you can go do something else for a little while, it's almost as good as a kitchen timer for allotting a certain amount of time to computer time.
So, Snap Links works for me! What works for you?