Lists of best apps are exceedingly useful. You find out what people like the best and don't have to take the time to try a lot of apps to see what the really good ones are. And one of the best lists of free apps that I've seen is iMore's recent list of Best free iPhone apps. Many of my favorites are here and are apps that I would also recommend. They've helpfully divided their list into the following categories: social networking, instant messaging & communication, educational apps, entertainment, financial apps, games, health & fitness, kids apps, music, navigation & location, news, photo apps, productivity, reading, shopping, sports, travel, and utilities.
In the entertainment category, I like Crackle, which offers free, advertising supported movies. Lately I've been using this app in conjunction with my Apple TV and AirPlay so that I can watch the movies on my 42-inch HDTV. They list The Weather Channel app under utilities, and this, too, is one that I use every day. A few months ago the app was completely redesigned, and I think it's intuitive, efficient, and excellent, especially the way that you can toggle between the 10-day forecast and today's forecast (including hourly). Plus, the interface is gorgeous, especially the way the background design changes to reflect the current conditions.
In the games category, they list Angry Birds Free, of course. This is the only game I've ever spent much time playing, and I can see why it's addicting. In the health & fitness category, they list RunKeeper. Ironically, I had just lately been thinking that I wanted to have an app that used GPS so that I could see how far I'm going when I'm out biking, jogging, or walking. I was even ready to pay for something, but now I've downloaded this one.
For news, one of their favorites is the immensely popular Flipboard, which I also like. It was a game-changer, organizing your news and social network feeds in a delightful and useful way. Just about everyone who tries it immediately says, "Wow, this is great." For shopping they select RedLaser, which was the first really effective barcode scanner. If you're in a store and find something you like, you can scan the bar code to get a sense for how much it costs elsewhere and whether it might be on sale nearby or available much cheaper on the Internet. It's been a very popular utility.
In the area of sports, the include ESPN ScoreCenter — an app that I can't live without. When you're desperate to know the latest score or want to track the progress of a game, this app is invaluable. You can customize it to show your favorite teams and sports. The travel apps they list include two that I've been impressed with. Yelp not only directs you to restaurants, bars, cafes, and more, but also includes a ton of user reviews for each listing. I tend to rely a bit more on a couple paid apps in this category, but Yelp is among the best of the freebies. They also include Google Translate, which is simply amazing. You speak in one language and it translates into another language. You can imagine how useful this would be for those traveling abroad.
All of these apps deserve a spot on your iPhone, and in my mind many of them are indispensible — I wonder how I ever got along without them. Most also have versions tailored to the iPad.