The internet is packed with information about Spring-heeled Jack. Unfortunately virtually all of it is second hand and woefully inaccurate. The following pages are worth a look:
http://www.geocities.com/jessnevins/vics.html
Jess Nevins’s Fantastic Victoriana site has a good summary of Jack’s appearances in contemporary popular fiction. Soon to be a major book.
http://www.mysterymag.com/hauntedbritain/index.php?page=
category&subID=7&unique=7007
Martin Jeffrey’s Mysterymag site includes information on several alleged recent sightings in the Midlands.
http://groups.yahoo.com/group/BloodsandDimeNovels/
The Bloods and Dime Novels group at Yahoo contains many useful and informed references to Spring-heeled Jack related Penny Dreadfuls.
http://www.geocities.com/justingilb/
Justin Gilbert’s Penny Dreadfuls site is a great introduction to the subject and features several SHJ images.
http://blackcatpress.co.uk/Spring_Heeled_Jack_Page.htm
Fortean researcher Steve Ash, who has been running Spring-heeled Jack walks in East London for a year, has put up a well-researched site devoted to the topic. It contains some interesting new speculations.