It comes down to one simple reason: I've never (literally never) had a project where mobile came first. I've never had a designer give me a mobile layout before a desktop layout. I've never had a client mention mobile anything in a first meeting (I always bring it up though).
Tyler Finck's Jonah font. I'm not really that sentimental.. but this is such a cute font!
Say you have a magazine-style WordPress theme. It has a slider that loads three posts, and then a list of recent posts. The issue of pagination come up when the user hits the Older Posts link. Maybe you have a front page that displays 3 posts in the slider.
I created this smart PayPal form for Trekkers.org. See trekkers.org/donate/. It lets the user switch back and forth between recurring and one-time donations. I couldn't find a free plugin that can do this. If this is installed on a WordPress or other CMS site, it is better set up as a plugin.
I like these: WordPress snippets to interact with social networks
WordPress comes with 2 taxonomies built in: Categories and Tags, but you can add Custom Taxonomies if you like. I was building WP sites for three years before I needed to set up a custom taxonomy for a client. There is a lot you can do with Categories and Tags.
If you want to put some related posts in a widget you can use the smart YARPP plugin. Or, if you merely want to list posts with matching tags, you can put a function in your WordPress theme. In some ways this is better than the fuzzy logic of YARPP because it gives you more control: you just give posts the same tag, and you know they are related.
The fad for icon fonts is a little silly, imo. I'm not that crazy about trying to replace all text on an app with a curious little picture. But, icons do have their uses, and I generally load Font Awesome on the sites I build, if I can use the social media, RSS, and gear icons.
This was a really nice project for me: a cool non-profit group, that wanted an upgrade of its old website to WordPress. Trekkers is an org that takes high school kids on bus tours around the USA. We created a site that had good balance between easy-admin, and rich news content.
Twenty Twelve is my favorite of the WordPress default 'twenty' themes. Its elegant and responsive. I like the smartphone menu. Twenty Ten is not responsive at all. Twenty Eleven is simply less classy. Twenty Thirteen looks like a good full-screen theme, but I have not yet done anything with it.