iSt at Menus $18 (approx £14)

bjango.com Activity Monitor is all well and good for checking your Mac’s resource usage, but its window isn’t exactly compact. If you’re keen to keep an eye on processes that might be hammering the CPU, thrashing your startup disk with activity, or using up a lot of memory, this app can display these and much more in the menu bar. Among the other things it can display are: info from your Mac’s fans and the temperature of components; your startup disk’s SMART status, which is normally tucked away in Disk Utility; and upload and download rates for your network connection.