I have had the chicken filled with tika masala or pepper sauce. Both very tasty.

You can't go too wild, then it won't be "kiev" anymore by definition:

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here are some variation

Try the following

Chicken Kiev
4 x 225g/8oz chicken supremes, skinned

For the Garlic Herb Butter:
45-60g/3-4tbsp freshly chopped flat leaf parsley
45-60g/3-4tbsp freshly chopped chives
1 tsp freshly chopped tarragon leaves
115g/4oz unsalted butter, softened
2 cloves garlic, peeled and crushed
salt and freshly ground black pepper
¾tsp English mustard

For the Kiev Coating:
50g/2oz plain flour
4 eggs, beaten
175g/6oz natural breadcrumbs
25g/1oz parmesan cheese
vegetable oil, for frying

Method
1. To prepare the garlic herb butter: place the herbs in a bowl and add the softened butter. To crush the garlic sprinkle a little rock salt onto a chopping board. Using the edge of your knife and using a paddling motion crush the garlic into a smooth paste. Add to the butter mixture. Add the mustard and pepper and mix together with a fork.
2. Divide the butter into four and set aside until ready to use. Plunge your hands into a bowl of cold water before moulding the butter. Roll each in greaseproof paper to form a torpedo shape. Place in the fridge for 30 minutes to allow the butter to harden. (The herb butter may be used with fish, meat and chicken.)
3. Place the chicken breasts, with the bone attached, smooth side down onto a cutting board. Remove the four baby (or excess) fillets and set aside. Make a vertical cut down the length of the chicken breast, but not all the way through.
4. Place the four breasts between cling film and bash with a rolling pin to ensure an even fillet. Repeat the process with the smaller (baby) fillets. This will stop any garlic butter from leaking out from the sides of the chicken.
5. Place the breast fillets onto a board, rough side up and season with pepper. Unwrap the garlic herb butter and place each garlic butter torpedo down the centre of each breast. Place the smaller fillets on top of the butter, pushing down to seal and roll up. Make a torpedo shape at the bottom of each fillet.
6. Place the breadcrumbs into a shallow dish. Grate the parmesan cheese directly into the breadcrumbs and mix together. Place the flour and beaten eggs into two separate shallow dishes.
7. Dip each chicken breast into the flour, making sure each is coated. Repeat the process with the egg, and then the parmesan breadcrumbs, making sure at each stage each breast is well coated. Chill for 30 minutes. Repeat and chill for a further 30 minutes or until ready to cook.
8. Heat the oil in a large pan or a deep fat fryer to 180C/350F/Gas4. Add the chicken breasts and fry until golden for 8-10 minutes and drain onto kitchen paper.
9. Serve immediately with herbed rice.

or Chicken kiev with herb mash
For the chicken kiev
500ml/17fl oz vegetable oil, for deep frying
50g/1¾oz unsalted butter
½red chilli, finely chopped
½ garlic clove, crushed
1 tsp fresh parsley, chopped
1 tsp lemon juice
1 chicken breast
50g/1¾oz white breadcrumbs
50g/1¾oz flour, seasoned with salt and freshly ground black pepper
1 free-range egg, beaten
For the herb mash
1 large potato, peeled and chopped
50g/1¾oz unsalted butter
2 tbsp cream
1 tsp fresh chives, chopped
50g/1¾oz grated cheddar cheese
salt and freshly ground black pepper

Method
1. For the kiev, heat a deep, heavy-bottomed pan, one-third filled with vegetable oil, until a breadcrumb will sizzle gently in it. (CAUTION: hot oil can be dangerous! Do not leave unattended.)
2. In a bowl, mix the butter with the chilli, garlic, parsley, and lemon juice.
3. Use a sharp knife to split the breast almost in half horizontally.
4. Open the breast out and place between two sheets of greaseproof paper. Bash the chicken with a meat mallet (or a rolling pin) to flatten the meat.
5. Place the butter mixture in the middle of the chicken. Fold over the meat so the butter is completely wrapped.
6. Dredge the chicken kiev in the seasoned flour, then dip into the beaten egg and then roll the kiev carefully in breadcrumbs. Repeat the egg and breadcrumbs process.
7. Carefully add the kiev to the hot oil and deep-fry for ten minutes. Remove from the oil and drain on kitchen towels.
8. Meanwhile, for the herby mash, boil the potato until tender, drain and return to the warm pan.
9. Add the butter, cream, chives and cheese to the pan and mash together well. Season, to taste, with salt and freshly ground black pepper.
10. To serve, place the kiev on a warmed plate. Slice open to release the melted butter and place a spoonful of herb mash beside.

or Chicken Kiev
4 chicken supremes
3 eggs, beaten
200g/7oz fine dry breadcrumbs
vegetable oil, for deep-frying
1 lemon, quartered lengthways
Garlic Butter
3 garlic cloves, finely chopped
3 tbsp finely chopped flatleaf parsley
1 tbsp finely chopped tarragon (optional)
125g/4½oz butter, softened
salt
freshly ground black pepper
1 tbsp lemon juice

Method
1. To make the garlic butter, put the garlic, parsley and tarragon (if using) in a blender with the butter. Season with salt, pepper and lemon juice. Blend to a smooth paste. Roll the butter in foil or cling-film and put it in the fridge.
2. Remove the skin from the first chicken supreme, laying it skinned side down. Detach the small fillet from the underside of the main fillet and cut this small fillet along its length and almost all the way through, folding it open before flattening
it by beating it gently with a rolling pin.
3. Put 15g/½oz of the chilled garlic butter in the middle of the small fillet and wrap the meat around it. Repeat with the three other small fillets, returning all four to the fridge once you've finished.
4. Cut open each of the larger fillets in the same way, place them between plastic sheets and gently beat them out with a rolling pin. Lay a small buttered fillet in the middle of each larger fillet and wrap the escalope around it.
5. Dip in beaten egg and then in breadcrumbs. Repeat to give a double coating. At this point it is best to refrigerate them to allow the butter to harden again.
6. Heat to high a deep-fat fryer or a pan containing vegetable oil and place the Kievs in the hot oil, turning to allow 4-5 minutes cooking time on each side. It is important to cook and handle the Kievs gently to stop them from falling apart.
7. When the chicken is cooked and a golden brown colour, remove and drain very well on kitchen paper.

Since Chicken Kiev is just chicken with an herbed butter stuffing...you could just use different herbs when making the butter....add lemon juice and lemon zest for a lighter taste, curry powder and a bit of minced up major greys chutney for an Indian variation....fresh mint and lime zest.....zing it up with diced jalapenos added to the butter.....just experiment.

Thet are all great, but not too healthy

I had a cheese and tomato filling one once
that was weird =|
and also i've heard of sausage and garlic ones