Oxford Reference Online [24/7] - [Can't get in?]
Newspapers - Most of the broadsheet newspapers have large 'Environment' sections with up-to-date news, articles, tips, and tools (such as carbon footprint calculators): Guardian: Environment | Telegraph: Earth | Independent: Environment

Recycling in Westminster - The Council's recycling pages have more than just a list of bottle banks - there's an A-Z of what can be reused / recycled and how, information on where your items go, a FAQ and seasonal information on topics such as Christmas trees.
Freecycle - Global network of local sites where you can advertise items you are happy to give away - and find items that others are giving away. All items must be free, and arrangements are made between individuals about picking them up. There is a local Westminster Freegle group.
Recycle for London - The Mayor of London's campaign to reduce waste in the capital. Lots of ideas, plus a recycling facilities locator.
walkit.com - Walking routes between two points, presented as text or as a map, with summaries of distance, time, and carbon expenditure avoided. Covers London and 12 other towns and cities. (When following the text from a printout, it is advisable to carry a map or street atlas, as directions can be approximate.)
Recycle Now - Information about recycling and how to reduce waste at home, at work and when shopping.

Naturenet - countryside & conservation - Up to date and clear information about many aspects of nature and the countryside in the UK, from tree surgeons to legal matters, and nature reserves to countryside jobs.
ENDS [Environmental Data Services] - Resources from the publishers of the influential ENDS Report, including a jobs service and a directory of environmental consultants. Articles from ENDS Report and ENDS Environment Daily can be searched, but full-text access on the site itself is by subscription only. Hard copy of the ENDS Report from 1991 to date is available at Westminster Reference Library.
Friends of the Earth - Information from the influential campaign and pressure group on environmental issues, including a searchable database of frequently asked questions.

Streetmap - Printable maps and street plans for the UK, searchable by place or postcode. Multimap also has overseas coverage.
Google Maps - Interative maps, with searchable locations (eg businesses, with full contact details) and driving routes. You can use the keyboard or drag the mouse to move around the maps, and can choose map, satellite or terrain view. You can even virtually wander the streets with Streetview.