The vmkernel logs (which log everything related to the kernel/core of the ESX) = /var/log/vmkernel.
The vmkwarning logs (which log warnings from the vmkernel) = /var/log/vmkwarning.
The vmksummary logs (which provide a summary of system activities such as uptime, downtime, reasons for downtime) = /var/log/vmksummary.
The hostd log (which is the log of the ESX management service of the ESX) = /var/log/vmware/hostd.log.
The messages log (which log activity on the Service Console operating system) is located at /var/log/messages.
The VirtualCenter Agent log is located at /var/log/vmware/vpx/vpxa.log.
The Automatic Availability Manager (AAM) logs = /var/log/vmware/aam/vmware_<hostname>-xxx.log.
The SW iSCSI logs = /var/log/vmkiscsid.log.
The System boot log is located at /var/log/boot-logs/sysboot.log.