When OS X reads a file, a timestamp is written to the drive. Disabling the read access time will reduce the number writes to you hard drive. Personally I really don't care about read access time, so I prefer to disable it. To do this create the file /Library/LaunchDaemons/noatime.system.plist with the following contents:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
(the first v in the -vuwo argument is for verbose and is optional)
After the file has been created, run the following three commands in the terminal.
sudo chown root:wheel /Library/LaunchDaemons/noatime.system.plist
sudo chmod 644 /Library/LaunchDaemons/noatime.system.plist
sudo launchctl load -w /Library/LaunchDaemons/noatime.system.plist
To verify the modification, run the command mount in the terminal and look for the line /dev/disk0s2 on / (hfs, local, journaled, noatime). If the last entry in the parentheses are noatime, the changes has been applied successfully.
If you have more then one partition on your disk, create a plist file for each drive and change the <string>/</string> argument to match the mount point for that partition.