Naturally you will bring your iPhone or digital camera or mini-video recorder complete with the necessary accessories such as memory cards, battery and battery charger.
Please bring several memory cards rather than one huge one. For instance, 5 4-Gigabyte SD/SDHD cards would be better than one 20-Gigabyte card. Cards can become corrupted, and you may never even know why. They just do. Why risk losing all of your precious photos?
By the way, while memory cards are available everywhere in Europe, the Middle East, and Mexico, they are much more expensive than here at home. Bring several. They are small enough they won't affect your luggage weight, and you won't find yourself out of available digital memory.
If your camera uses a rechargeable battery, then you will need either a dual-voltage charger or a plug adaptor for the charger according to the country you are visiting.
If your camera uses AA or AAA batteries, those are also available everywhere, even from street vendors. I prefer to bring a decent supply with me from home, and I bring the Lithium types made for digital cameras. Yes, they cost more, but they last longer.
Note: Lithium batteries must be transported in their original retail packaging, unopened (the ones IN your camera are ok; but do not allow batteries to travel "loose" in luggage. They may explode if their terminals touch).
Always visit http://www.tsa.gov for the latest restrictions on what you are allowed to pack in your luggage.
There you are! Have fun taking those photos. Share them with us, ok?