It depends on how familiar your friends are with uFAI tropes, so you may want to tone these up or down to keep foreshadowing at the right level. If they're highly familiar, you may want to switch paperclips with staples.

• Monsters attack a factory, which happens to manufacture binder clips.
• An infectious disease spreads across [home city], causing photosensitive epilepsy. Careful observers will note that seizures occur most often when lights strobe at computer monitor refresh rates.
• Corporate executives experience wave of meningitis (nanotechnology-induced). When they return to work, they cancel all paperless-office initiatives.
• Population of [distant area] missing. Buried underground: lots of paperclips. (If needed, have the paperclips test positive for some hallucinogen as a red herring).
• Iron mines report massive thefts, magnetism-related supervillain denies all responsibility and is actually innocent. Alternatively, if any heroes have metal-related powers, frame one of them and present false evidence to the players that a supervillain did it.
• Biotechnology companies seem to be colluding about something. The secret: somebody or something has been producing genetic material with their equipment, and they need to find out who, ideally without causing a panic. Maybe some superheroes could investigate for them?

If you do run this, please share your notes with us.

Edit: Now I want to run this sort of campaign. Thanks!