A pastry brush is a pretty handy accessory to have in the kitchen -- aside from glazing pastry, it's a useful tool for a perfect grilled-cheese sandwich. Just don't make the mistake of buying a super-cheap one.
In The Cook's Companion, renowned Aussie chef Stephanie Alexander provides a succinct explanation of why a pricier pastry brush is a better choice:
Choose a pastry brush with natural rather than nylon bristles to avoid melted bristles when working with hot ingredients.
Makes sense to me, though obviously silicon (like the brush pictured here) would also cope fine with heat. But seems like that's one kitchen item not to get from IKEA, then.