I'm trying to get better at design, which is really challenge for someone like me with limited aesthetic sense. It really helps to learn by example -- by studying what others have done. Most of the "Design Inspiration" websites seem to be aimed at marketing type sites, but I'm really looking for application or platform design inspiration. This is a community of builders who build just those types of platforms, so it's a logical place to ask:

Which apps, websites, or platforms do you look to for design inspiration? Who do you think really nails both user experience and visual design? Which platforms manage to both look beautiful and work great?