Nice post. Despite what others said, there's a place for a quick overview of Jekyll. The Jekyll wiki (which, have they updated it recently? It seems more useful than I remember it), while comprehensive, covers far more information than you need to get up and running. A quickstart guide would have been handy when I was starting.
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.
Very nice. It's like irc + upvoting? It would be interesting to hear what direction you plan to take it in. Are you going to keep it as a personal project or try to build it into something like HipChat?
I didn't try out your app as I don't personally have a need for an invoicing app on my phone, but it looks simple and easy to use. And I like the layout of your landing page.
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?
Great work on this. It's easy to use and fun to play with. I spent more time than I'd care to admit zooming in, panning around, and looking at all of the different impact sites.
(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 :)
Congratulations on launching your first store! I've always been a fan of vintage propaganda posters myself.
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.
Nice job! I like how this is an easy way to find common links on a particular topic (e.g. javascript). Are the links within a tag sorted by mentions? If not that might be a helpful addition.
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.