If you're planning a startup, DO THIS. Regardless of where you store your list (I use google docs), it is a great idea. You can drive a lot of users to your startup via a blog, but keeping a consistent publishing schedule is tough. I've stopped blogging consistently for the past 8 months while I've been working on my product. BUT, I now have a 26 page list full of blog ideas (I'll write a few sentences about each so I can remember the good points I have to make).
Now when I go to launch, I don't have to worry twice a week about what I'm going to blog about, I've got hundreds of ideas that I can just pull out my google doc :)