A good example would be the "new" i7 motherboards. They have triple-channel memory...that means a minimum of 6GB RAM. With 32-bit, it will not recognize that much memory....64-bit will.
It may take awhile, but eventually all the software developers will have to get on the bandwagon and make everything 64-bit; it is inevitable. 32-bit is getting very old.
Desktop: Intel i7 960 CPU @ 4.0GHz, EVGA Classified 4-Way SLI mobo, 12GB Corsair Dominator-GT 2000 DDR3 RAM, Crucial RealSSD C300 256GB Solid State Drive, Two WD 2TB SATA drives, 2x EVGA GTX 570 Superclocked graphics cards in SLI, Coolermaster HAF X full tower case, OCZ ZX 1250w PSU, Corsair H100 CPU Cooler
Laptop: MSI GT60-004US, 2x Seagate Momentus XT 750GB SSD Hybrid drives in RAID 0, 16GB DDR3 1600 RAM, GeForce 670M 3GB graphics card, Networks 'Killer' N-1103 WLAN card