General

Bruderhof Communities in the UK - communitarian Anabaptist groups
Church Net UK - extensive list of churches, Christian organisations and resources
CTBI - Churches Together in Britain and Ireland
Ekklesia - not-for-profit think-tank which works to promote theological ideas in the public square
Greenbelt Festival - UK Christian arts festival
Iona Community - ecumenical Christian community
emphasising spirituality, peace and justice
Leaving Münster - a mini-portal to a number of Resources on following Jesus in a post-christendom world (including a blog recording lessons learned and mistakes made along the way).
Living Word Library - London based guide to Christian web resources
London Mennonite Centre - rooted in the Anabaptist tradition, cultivating Christian discipleship as a way of life:

• Bridge Builders - offers mediation services and training/consultancy in conflict transformation for churches and denominations
  
• Cross-Currents Seminars- teaching programme of the LMC
  
• Metanoia Book Service - outstanding collection of Anabaptist titles as well as works on peace and justice

New Way of Being Church - creating processes for transformation in church and world
Simon Barrow - Theology and More... - Secretary of CCOM and Assistant General Secretary of CTBI - links to Simon's writings on issues of theology and society, religion and current affairs, and to related organisations

UK Christian Handbook - online version of UK Christian directory
Wood Green Mennonite Church - Mennonite Church in London
Anabaptist Studies - Lloyd Pietersen's Anabaptist studies blog
Workshop - national leadership and discipleship training programme

Mission

BIAMS
- British and Irish Association for Mission Studies
CCOM
- Churches' Commission on Mission - part of Churches Together in
Britain and Ireland (CTBI)
Urban
Expression - church planting initiative in
East London with an Anabaptist perspective
YWAM
- Youth With a Mission UK

Peace and Justice

Bradford
Department of Peace Studies - important and well known centre for
peace studies
Christian
Aid - agency
of the churches in the UK and Ireland, works wherever the need is
greatest, irrespective of religion
Christian
Ecology Link - multi
denominational UK Christian movement for people concerned about the
environment
Church
Action on Poverty - national ecumenical Christian social justice
charity, committed to tackling poverty in the UK
Churches
Criminal Justice Forum - inter-denominational
network designed to uphold Christian values in the field of criminal
justice
Council
on Christian Approaches to Defence and Disarmament -
believe that Christianity has a part to play in the debate about
peace and security in today's world
Centre for Contemporary Christianity in Ireland
- formerly ECONI
Environmental
Issues Network - deals
with issues relating to the environment and the world
Traidcraft
- leading fair trade organisation in the UK
SPEAK - a
network connecting the emerging generation to campaign and pray on
issues of global justice