When you go on a vacation, it's really nice to completely be disconnected from everything. While it's nice to be able to access the Internet, it's also very nice not to be interrupted or disturbed by the incessant vibrations of your cell phone.
When you work hard, it's really nice to be completely disconnected when you're on vacation. Obviously, not everyone can have this luxury, but if you can, it's definitely relaxing. Sure, expect to have your inbox filled with emails when you come back, but while you're away, it's good to log off and relax.
Most people work on computers a few hours a day, if not more. When you go on vacation, leave the laptop at home. Internet connections can be difficult to get in tropical countries, and Internet cafés are numerous, so if you really need to check your email, do so from there.
If you do take your laptop, try using it only for an hour or so a day to deal with daily emails, feeds, and other urgent notifications.
2. Cell Phone
If you leave the country to go to a tropical location, your cell phone might still work, but you'll be hit with big roaming charges. When you travel, communicate smartly using Skype or landlines if you need to.
3. Video Games
From time to time when I went on vacation, I took some handheld video games with me. After a while, I always got bored and I realized that I actually prefer reading a book for a few hours on a plane more than anything else.
4. Photography Hard Drives
There are a bunch of these devices that allow you to download your photos to a portable hard drive for safekeeping. Unless you're a pro, we'd stick with a laptop. You could also lug around a few extra CF cards for your camera.
5. Extra Lenses
Most photographers tend to use one lens most of the time, especially when they are on vacation. I've lugged around extra lenses only to never use them and stay with my 18-200mm VR Nikkor lens. Unless you plan on doing macro or have a super wide angle lens, leave the others at home.