I've eaten limpets and while they're a bit chewy I personally think they're quite pleasant. I usually cut them from their shells and remove the stomach etc., so that I'm left with just the fleshy foot to cook and griddle them quickly as you would scallops. I find long cooking just toughens them up.
Usually I just serve them simply as they're being cooked up right on the beach but I do have a couple of recipes you could try:
PASTAI BRENIG / LIMPET PIE (traditional Welsh recipe - allegedly)
A quantity of limpets, already cooked ¼ lb. of fat or streaky bacon
2 hard-boiled eggs
1 onion
Some bread dough or short crust pastry
Line deep pie dish with thinly rolled-out dough or short crust pastry. Fill dish with alternate layers of limpets, bacon cut up in cubes, sliced eggs and sliced onion. Add seasoning and a little of the limpet liquor. Cover with dough or pastry. Bake in a hot oven for ½ hour, and then more slowly for another ½ hour.
Limpet Pasta
Ingredients:
Several handfuls of limpets
1 lb pasta, precooked
1/4 cup butter
1/4 cup olive oil
5 clove garlic
1/2 cup chopped green onions
1/4 cup capers
1 tea fresh cracked popper
1/2 cup parsley
1/2 cup fresh grated parmesan cheese
1/4 cup white wine
2 lemons
Preparation:
Take several handfuls of limpets, washing and prepping them as described below.
Boil pasta or reheat preboiled in hot water in a colander. Place butter and oil in a wok. Add garlic and onions and sauté
Fill wok 3/4 with pasta. Toss until all strands are loaded with garlic oil. Add 2 to 3 handfuls of limpets. Add capers and pepper, followed with parsley, Parmesan cheese, lemon and wine.
Do not overcook the limpets, but serve when they are just al-dente but not tough. Adjust lemon to taste and serve
Grilled Fresh Opihi Limpet
Recipe courtesy Billy Wong
5 chillies
1 cup cider vinegar
1 cup water
2 cloves pounded fresh garlic
1 teaspoon sea salt
Butter
Soy sauce
Tabasco (optional)
Although this is a Hawaiian dish originally devised for the much larger Opihi, it can still be used for our own native limpets. It's also a good recipe to use with fresh oysters. Wash and prepare the limpets as described below. Mix chillies, vinegar, water, garlic and sea salt together. Marinate the limpet flesh in this mix for about 15 minutes before grilling.
While grilling add butter, soy sauce and if you like it, Tabasco. Serve with rice or cous-cous.
In Madeira, limpets are a traditional hors-d'oeuvre; the "lapas" are placed in sizzling garlic butter and become perfectly cooked in the time it takes to get from the kitchen to the table
Cooking tips:
Wash the limpets well; insert the point of a knife, run it round the inside of the shell and detach the mollusk. Remove any dark sections (head/gut etc.), place the meat on a work surface and tap it firmly with a wooden kitchen mallet to tenderize it without crushing it. Avoid collecting limpets during low tide if they have been uncovered for a long time, particularly in hot weather. While very common, limpets aren't used in cuisine very often because cooking can be tricky and if overcooked even by a few seconds, the flesh begins to toughen making it unpalatable however, marinading in mixes containing pinapple or lemon/lime will a slight softening effect on the meat.
There are a few books on edible seaweeds, try looking in Amazon but beware of American publications which might not suit your purposes. I have this one:
http://www.amazon.co.uk/Simply-Seaw...=sr_1_9?ie=UTF8&s=books&qid=1262476291&sr=1-9
but a local seal made an appearance near the fishing spot every evening! 
