Clutch pedal doesn't return properly
The problem: When the clutch pedal is depressed and released, it doesn't return to its original position. The clutch will generally still appear to work, but will feel wrong. It'll be stiff and grabby too.
The explaination: Moisture gets to a trunion that is meant to be self-lubricating, but which doesn't work that well. This helps it stick and stops the pedal from returning properly.
The solution: Get your head right down in the footwell, feet sticking out of the doors and lubricate the trunion. Use WD40, GT85 or a silicon based spray lubricant. Keep a can in the boot for when this happens miles from home.
Some people say WD40 is a bad idea because it displaces the trunion's own lubricant, but I haven't had any problems with it yet. Use silicon spray if you're paranoid. GT85 is like WD40 but contains PTFE too (teflon). It seems to need respraying less often with GT85. You can get it from bicycle shops for about the same cost as WD40.
Don't go nuts with the spray. A second or so of spray is enough to lube it back into smooth operation. Use too much and it'll dribble down the pedals and drip onto the floor, making a mess. Pump the clutch a few times after applying it too, to work the lube into the joint where it's needed.