This is what I had to add to my .bashrc to get Oracle drivers/sqlplus working:
#oracle stuff
ORACLE_BASE=/home/russ/apps/oracle
ORACLE_HOME=$ORACLE_BASE/10
TNS_ADMIN=$ORACLE_HOME/tnsnames
export ORACLE_HOME TNS_ADMIN ORACLE_BASE
LD_LIBRARY_PATH=$ORACLE_HOME/basic-client:$ORACLE_HOME/sql-client
export LD_LIBRARY_PATH
SQLPLUS=$ORACLE_HOME/sql-client/sqlplus