I’ve been a Dropbox user for about six months now, and it’s been pretty useful. I use it primarily to transfer files between my own computer and my computer science department lab account. It also comes in handy to share a quick picture online: dragging and dropping the file into my public dropbox folder is easier than opening a browser and uploading the picture to a hosting service. Still, it’s only been useful in a minor way so far, and hasn’t really done anything I couldn’t have done already with a little more effort.

That has changed. Enter the Dropbox iPhone app [iTunes link]. This app solves a problem I’ve been having, namely storing PDFs on my iPod Touch. A few of my professors upload their class readings online as PDFs, and before now I’d had no way of storing several PDFs on my iPod for offline viewing. The Dropbox app lets you not only access files in your Dropbox folder, but lets you download your “favorites” for faster (offline) viewing. This essentially gives my iPod the eReader functionality I’ve been wanting since I got it. I’ve tried other apps, like Stanza, for uploading PDFs, but I had too much trouble syncing. Stanza must be synced over a local wifi network, and my school’s network doesn’t seem to allow it. Syncing to the Dropbox app couldn’t be easier; it’s just click and drag.

The other problem the Dropbox app solves is transferring photos quickly and easily from the iPod Touch to my computer. Syncing my iPod with my Mac is a pain sometimes; half the time the computer refuses to recognize the iPod at all, and the other half of the time, it thinks it’s a camera and doesn’t open iTunes. Now I can upload photos from my iPod to my Dropbox account, and from there I can save them on my computer in less time than it takes iTunes to realize my iPod has been plugged in. Admittedly, this would be a more useful feature if I had an iPhone instead of an iPod Touch, but this feature did allow me to upload the screenshots I took quite speedily.

Unfortunately, the Dropbox app only lets you upload photos. It would be fantastic if it could upload notes as text files. If it had just this one extra feature, I’d probably pay about $5 for the app. However, the best part is that I don’t have to. It’s free!

Click to expand thumbnails of the app in action.

I don’t know how I ever lived without my iPod Touch. As a student on a campus with wifi everywhere, it acts just like an iPhone, but without the outrageous monthly fees and AT&T headaches. Here are my five favorite apps residing on my iPod:

iReddit
Price: $0.99

I am a big Reddit user. I tried the older open-source iPhone app for Reddit (known simply as “Reddit”), but it kept crashing. I’ve since shelled out a whopping $0.99 for the paid version, and I’m very happy with it. It loads quickly and crashes infrequently. I can check my mailbox and shake to get a random link. What more could you ask for?

Echofon (formerly Twitterfon)
Price: Free ($0.99 for Pro version)

This is a very fully-featured app, for being free. I can do anything on Echofon that I could from twitter.com on my computer, and even a little more. For example, Echofon colors unread tweets, which is a handier feature than it sounds. There is a Pro version for $0.99 that I haven’t tried that will sync tweets with their browser plugin, but I’m happy enough with the free version that I haven’t tried it. The app is ad-supported, but the ads are limited to a space the size of a tweet at the top of the screen, so they don’t bother me very much.

Yelp
Price: Free

If you haven’t tried Yelp at all yet, I highly recommend it. It lists and rates restaurants and stores in a given locale, so it’s great if you’re traveling or even just looking for a new place to eat around your home. The iPhone app is perfect because I usually don’t bring my computer along with me when I travel. It saved me in New York when the group wanted Eastern Indian food and in Montreal when we wanted French fare. The ratings are generally top-notch; people take the service very seriously. Overall, it’s a great service, and the app makes it super-easy to find businesses by location, by price range, or even by cuisine.  Each listing shows ratings, reviews, location, and phone number.

Sol Free Solitaire
Price: Free

I love this app because it’s simple, it’s free, and it does exactly what I want: play one-card-draw solitaire. It is ad-supported, but the ads do not get in the way of gameplay at all. The cards are easy to read and equally easy to move around. There are also no cheesy sound effects. The app also contains more versions of solitaire, such as 3-card-draw and Demon, but I haven’t played with them very much. Overall, this is a good implementation of a simple and fun game.

Wild West Pinball
Price: $0.99

I downloaded this app when it was free, and I couldn’t believe it was priced so low at the time. It’s an addictive little pinball game with an incredibly realistic physics engine. With the 2.0 update, they’ve moved the app to $0.99, but I still think it’s worth the price. They also improved a bunch of gameplay elements, such as fixing some of the most annoying traps in the game so the ball doesn’t get stuck there all the time anymore (I doubled my high score the first time I tried the new version). Just make sure you disable the music through the Settings app before you play; the included music is really cheesy and annoying. I keep the sound effects, though, considering how realistic they make the game feel.

What are your favorite iPhone apps? Tell me about them in the comments or send me an email!