George Mason University offers a great competitive opportunity. Their description is below, and the tuba repertoire includes:

EXHIBITION (no competition):
Beginner:
Open choice of exercises, solo, or other literature, totaling 10 minutes or less in length.

Advanced:
Suite for Tuba by Don Haddad (Shawnee Press/Templeton Publishing Company Inc.)

COMPETITION:
Tuba Student Soloist Level
Persiflage by P. Koepke/ed. H. Voxman
From the Concert and Contest Collection
(H. Voxman/Rubank Inc./Hal Leonard Corporation)

Air and Bourree by J.S. Bach/arr. William Bell
(Carl Fischer)

Concerto by James Barnes/Movements II and III
(Southern Music)


Details in Event Brochure

Description from the event brochure:

Set in the heart of Fairfax, Virginia, George Mason University will host the third annual Potomac Festivals Euphonium and Tuba Competition from June 20 to 23, 2006. This festival and competition is open to musicians of all ages and skill levels. The event is intended to increase the number of performance opportunities available to euphonium and tuba players, while offering them the opportunity to grow as musicians. In addition to the competition, clinics, master classes, recitals, concerts, and exhibits will be offered.
Each registered participant will perform for a panel of judges and receive written comments. Virtuoso Artist winners will perform in the final concert with the featured ensemble. No entry or evaluation tape is required. This event is open to all nonprofessional performers.