Log files: This option deletes the applications Logs, Terminal Command Log, and some System Logs.
bash Log: You can delete the log that contains the list of commands entered in Terminal using this option.
System archived logs: When the periodic scripts (daily, weekly, and monthly) are run, log files are archived and compressed. There can be up to seven archives per log. You can remove all of the compressed archives and some system–saved logs using this option.
Instant message logs: This option removes the saved conversations of the most popular Instant Messaging applications. Supported applications: Adium, AIM, aMSN, Colloquy, Fire, iChat, iRC, JBuddyMessenger, jIRCii, Messages, Microsoft Messenger, Proteus, Psi, Skype, Snak, Trillian, VChat, X-Chat Azure, and Yahoo! Messenger.
User Diagnostic Reports: You can use this option to delete all User Diagnostic Reports. The daily maintenance script also deletes these files, but only those that have not been modified in the last 60 days. Any web browser creates a FullCircle folder with two files: manifest.ini and permdata.box. These files can be sent when a browser quits unexpectedly and will be used by developers to diagnose and correct the cause of the issue. Each new version adds a new folder—making the previous one outdated. This option deletes the FullCircle folder located in the Library/Application Support/ folder in your home folder.
System Diagnostic Reports: This option deletes any Diagnostic Reports created by the system, and relaunches the syslogd daemon (process that records the activities of the system).
Mobile Devices CrashReporter: This option deletes any Diagnostic Reports that have occurred on your mobile device.