cheerleader
A couple things that might have been helpful would be to mention how to create new posts (since they have a specific format) and perhaps linking to a barebones deployment of Jekyll that followed along with your post (though you did link to your site, so kudos for that).
Keep on writing. A Jekyll plugin tutorial (as mentioned by ElongatedTowel) would indeed be a useful resource.
Keep up the good work!
What caught my eye was that the second feature you listed on the site is "localized." I wouldn't have guessed that many people would be looking for that in an invoicing app, but then again I only use a single currency most of the time :) Did you have customers asking for that or is it something that you felt they needed? Just curious.
I noticed you have something of an app empire in the making (http://chuinard.com/). How's that going for you?
Keep up the good work!
I also liked your write-up of the project: http://www.roadtolarissa.com/meteor-map/
(The only small, minor, nitpicky thing I noticed was hovering over a new impact site displayed the old one for a split second. You probably already knew that though :)
Keep up the great work. I can't wait to see the next iteration.
I ran into a problem though: I wanted to browse through the posters on the homepage but there were no links to do so. I was kind of wondering what to do next. (Your "Shop" page was more along the lines of what I was expecting with the links at the bottom.)
The posters seem a bit on the expensive side. Maybe there's a reason for that! Is it high quality paper, or do you offer incredibly fast shipping, or is there some other reason I should choose you instead of a competitor? Maybe your pages (should) have historical context for how or why the poster came to be and you're the historical poster expert.
Keep up the good work and keep us posted on how things go with your new store.
Keep up the good work.