Over the course of many years, I have found that it is difficult to find useful information... 

Below are some websites I would recommend for personal use: 



http://forums.chisham.com/                               This is a forum based website that has used/new instruments for sale,                                                                                auditions both professional and school based, and other useful                                                                                          information for tuba/lowbrass

https://www.musicalchairs.info/                         A job database regularly updated for an available job for any instrument,                                                                            tuba included!

http://www.iteaonline.org/index.php                 The "tuba/euphonium" website that every student MUST be a member of. With its                                                                                                 membership, it includes a variety of videos and resources that are applicable to everyday                                                                                 activites. It also includes recent job hires, great school information, recent events, and various                                                                           info on national and international competitions. 

http://www.potenzamusic.com/                         A great website to buy solos, and ensemble music for a variety of instruments. 

http://imslp.org/                                                 A database for a large majority of public domain sheet music available for                                                                                                           immediate use/print. This is a great website for all musicians, whether vocal or instrumental.