Online Metronome:

http://www.webmetronome.com/

Drones for intonation work:

https://www.youtube.com/playlist?list=PL89F14447A668A805

Scores and parts for most orchestral and trumpet pieces published before 1923:

http://www.imslp.org/

Collection of some of the commonly asked excerpts in orchestral auditions. With clipped recordings and parts:

www.trumpetexcerpts.org

The Bulletproof Musician - Useful tips for dealing with Music Performance Anxiety

http://www.bulletproofmusician.com/#

Getzen Instruments:

http://getzen.com/

Edwards Trumpets:

http://www.edwards-instruments.com/trumpet/index.php

International Trumpet Guild:

http://www.trumpetguild.org/

National Trumpet Competition:

http://www.nationaltrumpetcomp.org/

Musical Chairs - An index of the impending trumpet auditions worldwide:

https://www.musicalchairs.info/trumpet/jobs

Online Music Dictionary:

http://dictionary.onmusic.org/