There is always something to do around the GNOME FreeBSD camp. Grab something that sounds interesting to you, and run with it.
Test existing ports, and report bugs. Try to build with weird configurations intentionally, before someone else tries to do so cluelessly.
Regularly install GNOME from packages, and report any problems with the install or the functionality.
Find GNOME applications not yet ported to FreeBSD, and work on porting them over.
Subscribe to the freebsd-gnome mailing list, and help answer users' questions.
Proofread the FreeBSD GNOME project pages, and offer feedback and updates.
Build, upgrade, and rebuild both stable and development versions. The builditinator.sh script, available from the MarcusCom portstools repository, can automate the entire process, from start to finish.
Send any feedback to freebsd-gnome@FreeBSD.org.