A feature packed layout tool that grows on you. Used by many many websites.

Let panels take over the whole page. From d.o:
"Panels Everywhere is an advanced method to completely do away with Drupal's restrictive blocks system and instead use the much more freeing Panels Layout system to control how your pages look. Panels Everywhere modifies the page as it is being rendered to 'wrap' the content in a display and can even take over your page theme to do away with the need for a page.tpl.php."

Dave Reid's alternative to Display Suite and other display modules.

Maintained by Dave Reid, Earl Miles, Damien McKenna and Derek Wright

Semantic Panels let's you control the markup of panels.

This module uses the FitVids.js library for fluid width video embeds (e.g. flash video in <iframe>s). You don't need it for pure HTML5 videos.
It supports YouTube, Vimeo, Blip.tv and Kickstarter by default, and can use it with other video providers like Dailymotion or Viddler.

Smart Trim implements a new field formatter for textfields (text, text_long, and text_with_summary, if you want to get technical) that improves upon the "Summary or Trimmed" formatter built into Drupal 7

Here's a SASS snippet for making cross browser rgba gradients.

Sometimes Display Suite will render fields out of order. Use hook_ds_pre_render_alter() to change the order.

This module is basically an advanced devel generate (see the devel module). Gives more control over the dummy content that gets generated by devel. (I haven't used it yet but it seems promising.)