Further resources for your own repertoire
My list might be useful if you are looking for repertoire to explore, especially if you want to play music written in the last hundred or so years. We all have musical preferences, however, and this particularly governs our choice of commissioned composer and concert music generally. Here are the websites of two great cellists with some very different repertoire to mine, especially with regard to the composers they commission:
Frances-Marie Uitti: www.uitti.org/index.html
Arne Deforce: www.arnedeforce.be/
Internet: there are many other cellists out there, all with their websites, audio and YouTube clips! (See Recommendations section for my own favourites)
ESTA is a great source of ideas for cello music of all standards. Membership has many other benefits too.
Then attend as many concerts as possible (mine, even!) and talk to as many composers as possible and find what appeals to you.