Electronic:
Underworld, Plaid, Fluke, Aphex Twin, Basement Jaxx... to name a few.
The Warp label is a good starter:
http://en.wikipedia.org/wiki/Warp_Records
http://de.wikipedia.org/wiki/Kategorie:Techno-Band (only in German, but you have a good list to start)
Most of the best and most sophisicated techno comes from UK (in contrast to most EU continental techno like Scooter and other crap).
The continental Europe is better at "mellow" electronica (e.g. Kruder&Dorfmeister/AUT, Mouse on Mars/GER, Alex Gopher/FRA, Daft Punk/FRA...)
R&B:
Thousands of great artists over the past decades, too many to mention them all. To name just a few: Marvin Gaye, Stevie Wonder (except only one song: I just called to say I love you), Aretha Franklin, Prince...the list goes on forever.
But if you meant modern R&B, I think only the ladies are really worth it, e.g. Alicia Keys and - especially - the brilliant and outstanding Erykah Badu.
