We used to see them on glossy paper magazines. Pull quotes could make important parts of the content stand out, and effectively draw an outline of it the same way titles do. When a bit more sophisticated, they could add rhythm and color and make your content pop. Lately, I've started seeing more and more of those on the web, the last I can recall being the gorgeous theverge.com.
Displaying a twitter feed on a website is easy as pie. Especially when you're using one of the top 5 CMS out there, chances are someone has already sorted it out for you and made it a module easy to plug in. It's the case with Drupal.
HTML is hard to write. So many of those hard to reach characters can drive you crazy if you don't get some help from your editor. My advice is not writing naked html at all, but instead give a try to Haml. But you don't always get the chance to use the tools you want.
Ever since @font-face joined the game, designers had no longer to adhere to a particular set of web-safe font, letting them express their creativity with any typeface they like. But having to ship copyrighted font files to some client machine is by no means unproblematic. Fonts are software and even though you paid for a license, you can do no more with it then what is specified in the EULA.
I see a lot of people give me a specious look as I'm telling them I use Vim for web development, and some of them are the most experimented programmers I know. They do admit that Vi is that thing that might save you from some complicated situation sometimes, when you have this server than wouldn't boot, everything could be broken but Vi is still there ready to work. It's because it's so lightweight and it needs almost nothing to start running. And that's why server admins love it so much...
I have one weakness. Probably thousands more but the one I am thinking of at the moment is one that I have managed to deal with: I am not good at sorting files on my computer. It's not that moving files into folders requires special expertise, but not doing it frequently certainly results in monumental mess.
Of all my folders the most damaged by my laziness is probably my downloads folder. Over time, I download so many files and garbage: dozens of randomly named pdfs, hundreds of mysterious zip archives with their unzipped folders 10 scrolls away.