Campsite book with a discount card for early and late season camping comes with map of Europe with all the sites indicated.  The 2007 book at £6.50, contained 1,134 camp sites in 17 European countries, discounted to 10€, 12€ or 14€ / night.  DVD also available.

See their web site for details

Me

A lot like the book above sadly without the discount card but with 4,100 campsites in 25 countries, got it very cheap in Aldi or Lidl.

Me

The Rough Guide to books, are a good way to find sites close to town centres, they also offer suggestion on reasonably priced eating places.

Trouble is you have to have the book for the countries or region you are travelling to.  Can often be found second-hand on eBay for very reasonable prices or look out for them on offer.

Me

The Lonely Planet books, are very similar to the Rough Guide to books and are therefore just as useful.

Same applies to buying as above.

Me