Backpack:
iPad, pen, spare cufflinks, hand cream, lip balm, glasses, baseball cap (for sunny days), LoZ Beanie (for rainy days), spare socks (rainy season in Shanghai can have water up to 12 inches in about 30 minutes and the downpours can be sudden), plastic shoe covers (again, lost too many shoes to rain), keys, umbrella and collapsible police baton. I've never had to use it, but there have been several cases of nationalistic Chinese going after foreigners for no good reason over the last twelve months.
Pockets - phone, wallet, travel card for public transport and that's about it.