I suggest keeping a text file handy, and inputting urls of the post whenever you would like to merit something, but can't due to exhausting your merit pool. Of course, this requires manual work, but at least you get to review whether you think that post deserves merit or not. I've kept a text file full of posts which I haven't gone through completely yet despite now being a merit source.
I already have a text file filled with links and I collect them very often when I run out of sMerits. For me it's very handy rather than using and extension or such thing.
Bookmarking is the right way to do it. Or
just leave 300 tabs open You mean to say - do not shut down the computer? :-P