When I'm kinda bored, but sitting at the PC, I'll take an envelope or advertising cardstock, and skootch it between the rows of keys to push the cat hair all the way to the end of the lowered section, and gently lift it out. Only after going horizontally and then vertically in ALL the rows (vertically only works for the numbers keypad) will I then turn the keyboard over and thunk it around to get the bits of crud out.
Then I use a can of compressed air to blow more gunk out. If I've not found something else to do by then, I'll get a cleaning wipe and futz with the keys and flat spaces to get the schmutz off everything.
I think this whole process occurs about every month or so. In between times, I'll whack the keyboard upside down to move that stubborn whatever-it-is that prevents just one stupid key - usually the m, or sometimes the c - from performing its role in written communications.