Alright let's get a 3DS friend code exchange going. I'll update this list as people add their own friend codes.
Format: DP username: 3DS friend code (usual games)
- c0ldb33r: 4339-2478-4186 (Super Street Fighter IV 3D Edition, Pilotwings)
- deltoidsteep: 0430-8273-7852
- maxlords: 1246-8719-4860
- nz17: 4296-2977-3565 (Super Street Fighter IV 3D Edition)
- meancode: 3609-1033-1324 (Ridge Racer, Ghost Recon)
- killersquirel: 1118-0232-4338 (Steel Diver, Pilotwings)
- Wolfrider31: 4511-0467-1912 (Pilotwings)
- -dustburn-: 1891-1176-8170 (Pilotwings)
- nickerous: 0688-5264-2231 (Super Street Fighter IV 3D Edition)
- hellfire: 1118-0260-4743 (Super Street Fighter IV 3D Edition)
- Fredoche711: 1977-0181-1473 (Super Street Fighter IV 3D Edition, Pilotwings)
- mattimeo: 4897-5967-3681 (Super Street Fighter IV 3D Edition, Pilotwings)
- Lothars: 2664-2261-4686
- Robocop2: 2793-0781-0569
- Ludwig: 4596-9692-2482
- TinyTheGiant: 4682-8598-5541
- videogameking26: 4639-8979-9850 (many)
- creacked8ball: 1418-6799-5446 (Mario Kart 7, Dead or Alive: Dimensions, Resident Evil Mercenaries 3D, Tetris: Axis)
- ladyjaye: 0001-3701-0558
- Atar1G1rl: 2535-4104-2442
- Queen of the Felines: 3308-4993-4867
- Pantera18: 1934-1215-1966
- joshnickerson: 0473-8317-6182 (Super Mario 3D Land, Mario Kart 7)
- dustburn: 1891-1176-8170
- shertz: 5370-0932-2395 (MK7)
- Rampagou One: 4682-8957-7717
- Slipdeath: 1805-3053-7836 (Kid Icarus)
- GeneticsDave: 4081-6155-6434
- Genesaturn: 1289-9502-7134
- BetaWolf47: 5155-4269-3180
- Nz17: 4296-2977-3565
- YoshiM: 0860-4642-4923 (Kid Icarus)
- Dustin: 2509-1676-5493
- ShinobiMan: 4270-1159-9427
- Lict: Code: 5215-0757-8493
Don't forget, both parties will have to add each other. The 3DS won't prompt you to add someone just because they've added you.