I have 7 year old and 4 year DS, some of the things the enjoyed last year were:
Marvel Action figures
Teenage Mutant Ninja Turtles figures
smashaballz
Teenage Mutant Ninja Turtle Combat gear
Robofish
Roald Dahl book collection
Any Games-Whack a Mole, Buckaroo, Hungry Hippos etc
Skylanders
This year my 7 year old is mainly into Fimo clay (he enjoys making models) and Minecraft so got him lots of figures to that, also got him a Mario chess Set, Meccano Set, John Adams Hotwires Set, Lego Movie Lego sets, a digital camera and lots of arts and crafts items
My 4 year old has Transformers, Despicable Talking Minion, Lego Juniors Sets, Playmobil Police sets, Marvel Mashers and Imainext Dinos plus arts and crafts items