A post from Programmers.SE has given some very useful links in answer for Design stuff:

http://programmers.stackexchange.com/a/32720/43851

• http://www.456bereastreet.com/ (accessibility)
• http://www.alistapart.com/ (web design, standards)
• http://www.drawar.com/ (design community, articles, showcases and forum).
• http://www.lukew.com/ff/ (interaction design)
• http://37signals.com/svn/posts (web app design, inspirations)
• http://www.smashingmagazine.com/ (showcases, freebies, articles)
• http://typography.com/email/2010_03/index_tw.htm (typography)
• http://retinart.net/ (graphics design)
• http://cssglobe.com/ (frontend dev)
• http://ilovetypography.com/ (typography)
• http://www.uxbooth.com/ (User Experience)
• http://scriptandstyle.com/ (frontend dev)
• http://www.thegridsystem.org/ (layout)
• http://52weeksofux.com/ (User experience, design)
• http://tutsplus.com/ (tutorials)
• http://www.zeldman.com/ (web standards)