I would suggest the fix is to carry a smartphone at all times rather than a notebook. The phone fits in your pocket and odds are you might need one anyway.
I would add to use Evernote on that phone. Evernote makes the notes searchable and syncs them.
I suggested recently that part of the problem with with LW was a lock of discussion posts which was caused by people not thinking of much to post about.
When I ask myself "what might be a good topic for a post?", my mind goes blank, but surely not everything that's worth saying that's related to rationality has been said.
So, is there something at the back of your mind which might be interesting? A topic which got some discussion in an open thread that could be worth pursuing?
If you've found anything which helps you generate useable ideas, please comment about it-- or possibly write a post on the subject.