As most people said, eels will take just about anything, but something like fresh offal (fish or animal guts) or fresh meat of any sort is best. I've caught most of my eels on worms, grubs, fish meat or freshwater pippies. Keep your bait right down near the bottom and remember a decent sized hook and heavy leader. You can leave a few of these 'eel lines' out for many hours because the eel will usually swallow the bait quite deep down his throat, and with the heavy line that you use you can still haul them in hours later cos they wont get away.
Another good way to catch them is to make an 'eel bag'. Get an old hessian bag (do they make these anymore?) and put some bloody/smelly meat or offal in it. I used to use a shot rabbit or cut off piece of kangaroo meat. Simply tie up the end of the bag with heavy string or rope and chuck the bag in the river, tieing off the rope to something on the bank. The eel will chew a hole through the bag and wriggle in to get at the meat, but after having a good feed will not be able to find his way out, hence be still wriggling around in there when you pull in the bag in a day or two.
