iStat Menus lets you monitor your system right from the menubar. Included are 8 menu extras that let you monitor every aspect of your system.

• CPU - Monitor cpu usage. 7 display modes, multiple core support.
• Memory - Monitor memory usage. 4 display modes, page ins/outs and swap usage display.
• Disks - Monitor disk usage and activity. 6 display modes, ability to hide disks you dont want to see.
• Network - Monitor current and total bandwidth, peak bandwidth, ip addresses, and the ability to hide network connections you don't want to see.
• Temps - Monitor the temperature of your mac. 2 display modes, ability to hide sensors you dont want to see.
• Fans - Monitor the fan speeds in your mac. 2 display modes, ability to hide sensors you dont want to see.
• Bluetooth - Control bluetooth status plus monitor the battery level of your Apple wireless keyboard or mouse.
• Date & Time - Date + time in your menubar. World clock display lets you see the time in multiple locations around the world.

• Added support for late 2014 iMac and late 2014 Mac mini.
• Added ability to customize menubar graph background opacity when using Yosemite's dark menubar.
• Fixed menubar dimming on secondary displays on Yosemite.
• Fixed an issue with week numbers being incorrect in some timezones.
• Fixed an issue with the calendar month name being incorrect in some timezones.
• Fixed an issue with minimum fan speed on some models.
• Fixed a battery menubar display bug with dark mode in Yosemite.
• Fixed an issue with Czech localization.
• Fixed some process display issues on Yosemite.
• Fixed a bug with default disk activity colours being back to front in preferences.
• Fixed a problem with graphics cards not being listed on 2013 Mac Pros.
• Fixed a problem with graphics card monitoring on some iMacs.
• Improved rendering of menubar calendar numbers.
• Improved battery icons.