Google Maps offer clear maps with lots of route & business finding stuff, street names & detailed satellite images. Now includes Street View images.

Natural England & Defra provide a view of environmental information from across government. It is much more a Geographical Information System (GIS) than a simple map - there is a huge amount of information here.

Initially showing a local view of Ancient Woodlands, Nature Resrvers, Scheduled Monuments, etc. Topics available cover Access, Rural Designations, Habitat Inventories, Landscsape and much more.

The Environment Agency has maps showing local flood risk, landfill sites, river basin management and more.

Ordnance Survey's Get-a-map. A proper map at 1:25,000 scale like a small (2km) window onto one of the Explorer (orange cover) maps.

Good, big, OS 1:50,000 scale - like a small (3km) window onto one of the Landranger (red cover) maps.

The Wikipedia of maps, OpenStreetMap is a free editable map of the whole world. It is made by people like you.