The key process logs are as follows... (replace <user> with the user that started the service, and <hostname> for the machine name)
NameNode: $HADOOP_HOME/logs/hadoop-<user>-namenode-<hostname>.log
DataNode: $HADOOP_HOME/logs/hadoop-<user>-datanode-<hostname>.log
JobTracker: $HADOOP_HOME/logs/hadoop-<user>-jobtracker-<hostname>.log
TaskTracker: $HADOOP_HOME/logs/hadoop-<user>-jobtracker-<hostname>.log
HMaster: $HBASE_HOME/logs/hbase-<user>-master-<hostname>.log
RegionServer: $HBASE_HOME/logs/hbase-<user>-regionserver-<hostname>.log
ZooKeeper: TODO
For stand-alone deployments the logs are obviously going to be on a single machine, however this is a development configuration only. Production deployments need to run on a cluster.
The NameNode log is on the NameNode server. The HBase Master is typically run on the NameNode server, and well as ZooKeeper.
For smaller clusters the JobTracker is typically run on the NameNode server as well.