23) Buy frozen finger food and put into oven in staggered batches. When a batch is ready, immediately transfer to serving tray and walk through party offering people food. Great task to delegate to that one attendee who doesn't know anyone!
24) Polaroids/Disposable cameras are cheap and seem to be universally adored. Get a few and scatter them throughout the party.
25) Sharpies/labels for marking solo cups, drastically cuts down on clutter as the night goes on.
26) If someone brings a bottle of wine or a bottle of liquor as a gift, just crack it open and ask them to share it with other attendees. Same with food. Makes for a good conversation starter.