Updated april 24 2010

A Cadenza (italian for cadence) is “an extended, improvisatory style section inserted near the end of movement. The purpose of a cadenza is to give singers or players a chance to exhibit their technical skill and – not last – their ability to improvise. Since the middle of the 19th century, however, mostcadences have been written down by the composer”. (from Lilypond music glossary)
A drum cadence: “a drumline piece played in a parading marching band between or in place of full-band pieces”. Cadences, are also: “a chant that is sung by military personnel while parading or marching”. Mix all off this stuff and play. Here some resources (check this post for updates):

Theory

• A study of the Rudiments used in foreign military drumming styles: a pdf file with 18 gold pages. A deep study of european military traditions (from France to Duch, from German to Scottish) in drumming, drums notation and rudiments. Leading to a 57 international rudiments system
• The perfectionists. The History of Rudimental Snare Drumming, From Military Code to Field Competition

Sheet, music, community

• Ocpd, Ossessive compulsive percussion disorder: the drumline sheet music paradise. Cadences, exercises, warm-ups, battery music from the best Usa drumlines (Blue Knights, Cavaliers, Colts, Esperanza, Madison Scouts, Glassmen, Blue Devils and many, many more)
• Drumlines.org – Cadences forum: discussion, mp3 file, sheets. One of the best place to get ideas and discuss with other (snare) drummers

Other Cadences and drumline sheet music links:

• MarchingPercussion.com: free music for marching percussion
• Cadences from the movie Drumline, transcribed by drumlines.org members (.png file): first game cadence, and Sean solo
• Cal percussions exercises and cadences by the Drumline of University of California marching band
• Dickinson State University Drum Line: warm-ups and Cadences
  2003-2004
• Drumline exercises from McKinney Boyd High School Percussion, 2008/2009
• CHS Drumline Auditions 2008
• Mississipu State University Drumline, tons of music from 2002 to download – and study – for free
• 
  Free Marching Percussion Drumline Sheet Music
  Free cadences exercises arrangements marching percussion drumline sheet musicby Cassidy Byars
• 2008 UC Drumline Technique Exercises and Drum Break Book
• Texas drumline marching percussion handbook 2009-2010: warm up, hands studies, breakdown, exercises. Great book

Rudiments

• The Percussive arts society (PAS) 40 fundamental rudiments
• Hybrid rudiments
• Swiss rudiments: the famous Swiss rudiments system
• The Drummers’ and Fifers’ Guide by Bruce and Emmet, 1961
• The trumpet and drum by Philip Sousa, 1886
• Rudimental variations: page1, page2
• Rudimental exercises: endurance, coordinative, warm up, chops

Certificates, manuals and drumline auditions sheets

• Drumming Curriculum and Guidelines, Intermediate & AdvancednSnare Drumming: Royal New Zealand Pipe Bands’ Association
• Troopers 2010 audition packet
• Illini drumline audition packet

[For other drum cadences, rudiments, exercises and warm-up, you can also browse the rudiments category]