Ooooh where do I start?!!
FOOD
Jade Restaurant along western road, £13 for all you can eat and it's freshly prepared to order!
Wagamamas in town down the North Laines - I reccommend number 38
Nandos on Duke Street, Lanes
Mongolian BBQ, South Laines - This place is fab, they give you a menu of recipes, then you go up and pick out your own mean, and ingredients then take it to be cooked on the flat grill. You can stick to their reccomendations, or make up your own recipes, just make sure you add enough stock! think its about £13-£15 for all your can eat here too
Food for Friends - South Lanes, this is veggie but the food is soooo nice! Or there is a Zizzi across the road.
Gourmet Burger Kitchen, North Laines - I reccomend the Satay Chicken Burger
SHOPPING
Like Steelgoddess said, check out the Lanes. The South lanes are nearer to the coast side with lots of jewellers and designer shops and restaurants. North Laines is the lesser know part and has some great little independent shops. Then there is always the mall, Chruchill Square Shopping centre.
VISIT
Brighton Pavillion
The Brighton Centre, The Theatre Royal or Brighton Dome- not sure whats on there at the moment, but worth checking out.
Komedia comedy club, down North Laines - always have performances on Fridays, Sat and Sunday - Sunday is £10ish for about 4 hours of great comedy with a mix of comedians, serves good food too. Be sure to book in advance and arrive early, gets very busy.
The Pier - theres bar, food and games and rides!
If you get a chance, just take a stroll from the beach right along the seafront (beside the beach, rather than the prommenade) theres shops, bars, stalls, vollyeball court, basketball court, playground, even a gym!
Hope that helps!