I make a lot of use of TfL's Journey Planner at
http://journeyplanner.tfl.gov.uk/user/XSLT_TRIP_REQUEST2?language=en.

It has recently become "infected" with advertisements.

I find those advertisements intrusive enough to stop them.
The final straw was a cookie from the Australian version of Ebay.

On a Vista machine, I added the following line to
c:\windows\system32\drivers\etc\hosts
127.0.0.1 ad.doubleclick.net # Eliminate Journey Planner ads

This causes links to ad.doubleclick.net to be satisfied by the local
machine (127.0.0.1). It returns nothing and so,
the consequence is that large areas of white space are put on the screen
in place of the adverts. All files from ad.doubleclick.net are
eliminated and there is a risk I will miss something valuable.

I used Vim to do the editing.

Those without the ability to edit the file directly, should be able to:
1) Rename hosts to hosts.txt;
2) Use notepad to add the line above;
3) Rename hosts.txt to hosts, saying "Yes" to "If you change a file name
extension, the file may become unusable. Are you sure you want to change
it?"

It may be wise to backup the original file to avoid risking damage which
is hard to fix.
--
Walter Briscoe