What to consider:
Like toddlers, three to five-year-olds still love pretend and role play. Concentration spans may well be improving, so sit down activities such as puzzles and arts and crafts are popular, but equally, physical toys bring good play value, as preschoolers have plenty of energy to expend.
Children this age tend to have more developed likes and dislikes than their younger counterparts, so it's worth getting ideas from them about what they might enjoy (although hand them a toy catalogue and ask for preferences at your peril – they'll probably say 'all of it'!)
If you don't want to ask for specific present requests, do try and get a sense of what kind of child you're buying for if they're not your own. As before, avoid assuming all girls adore dolls' houses/ princess/ fairy toys and all boys love toy guns/ soldiers.
Pre-schoolers will be beginning to learn skills which are pre-cursors to reading and writing later on. They might start to get interested in letters and counting or enjoy putting crayons to paper – there are tons of fun but educational toys out there which can help with all this.
Parents might appreciate clothing as a gift for their fast-growing child but be warned, unless it's something which really appeals to the recipient themselves, that T-shirt or sweater might be opened and immediately cast aside for a toy.