My favorites:

https://labnotes.org/ - fantastic, weekly summary on design, frontend, architecture, business, and some humor.

http://rubyweekly.com/ - a roundup of announcements, new gems, talks and more

http://www.evilmadscientist.com/tag/linkdump/ - monthly list of links related to science, hardware hacking, geekery

http://randsinrepose.com/ - a few posts a month, great advice and thinking about tech and team management.

http://consumeconsume.com/ - funny pictures of irony and shock, which always give me great material for tech presentations

For RSS->email I use IFTTT