I have been using Dropbox for some time now; installed the Mac App and the iPhone App and I just use it on a dily basis for exchanging files with friends, links with myself, uploading stuff for others to download, and storing files to be accessed from everywhere. It's like an online "flash drive" accessible from everywhere as long as you have an internet connection. The free version gives users a good 2GB of free space, while you can purchase more space from the Dropbox website. Apps are available for iPhone, iPad, Android and Blackberry phones.
Read It Later is probably my favorite thing these days, I'd say it's as awesome as the invention of the command-Z feature. It was brought to my attention via the official Twitter app for the iPhone where there's an option for saving links off of tweets to a list to be read later. When I registered for an account I noticed that you can use it with while browsing (by installing a third-party extension to your browser) and it's like the best thing since sliced bread! Really it's like building your reading list with just a few clicks. I haven't used the iPhone app that much, mainly because I find it sort of tedious reading off websites on the iPhone, but the mobile app has an awesome feature, that of saving the articles for offline reading.