My personal recommendations, you should follow them!

"Vips":

@TomFelton
I don't have to say anything about that, do I?
www.tomfelton.com

@SixStringProd
Seems to be VERY connected to Tom ;)
I think we will see news about his
music there soon!

@GreatOrmondSt
Great Ormond Street Hospital provides inspirational and world class care
to hundreds of children every day. 
But they need to raise over £50 million every
year to help keep the magic alive
www.gosh.org

 @RobinHood
The Robin Hood Tax is a tiny tax on banks, hedge funds and
other finance institutions that would raise billions to tackle poverty
and climate change, at home and abroad
http://robinhoodtax.org.uk/

@FilmClubUK
FILMCLUB is a network of exciting after-school clubs which offers children free
weekly access to thousands of classic and popular films - opening the door onto
a dazzling world of cultures, life stories, aspirations, times and places. 
For further information please visit www.filmclub.org

Fansites and Fangroups:

@TomFeltonMedia
Biggest Tom Felton Media archives I know

@TomFeltonInc
Quite new but great British site for Tom

@Feltbeats
Biggest and best known fan site for Tom

@TeamTomHP
Great team of lovely Tom fans

@TFeltonFil
Tom Felton fans from the Phillippines

More coming soon :)