Talking to merchants around the world lets you learn about the many unique ways they need to run their stores . On example of this is a recent email I had from a merchant in the Netherlands that wanted to show BTW instead of VAT in notification emails.
There was a recent post on the Shopify eCommerce forums where someone asked how to change the sort order of products in the Admin (not the storefront). I can actually see the use case for this but thankfully a simple url change can make it happen.
Shopify Liquid has allows you to change the formatting of the date string but the default output is English. If you want to change the days or months to be shown in another language you'll need to translate it.
Persistent cart is an interesting concept: On one hand I like the idea of a session that expires with the device I am using. On the other I see why merchants may want a cart that acts more like a saved wishlist.
If you're someone that has a Shopify site but runs an offsite blog (like wordpress) you'll probably want to be able to show the cart contents on that blog. The usual AJAX API calls won't work since you'll hit CORS errors but JSONP comes to the rescue.
Freakdesign has worked with some pretty cool clients (some noted below) - all different sizes and sectors. From Brisbane, Sydney, Melbourne through to worldwide, there's few places our work hasn't been. Even the work has been varied with Shopify designs, EDMs, Branding, Illustration and everything in-between. Nice to have variety!