I have now had my Sprint EVO 4G for almost three weeks. It is my first Android phone, and I have found a ton of apps that I find make the experience better. In fact I have gotten so used to some of them that I would probably find using the EVO much more difficult without them.
AppBrain -- I'm sending along links to the AppBrain store. If you aren't using AppBrain, I recommend it first. It helps you find apps you might want from your computers web browser and queue them up for installation on the Android when you want to. Go directly to the Android Market on your phone to install it.
Dolphin Browser HD -- The internal browser for Android is pretty good, but this browser adds so much more. Tabbed browsing with up to 8 tabs open at the same time. Gesture controls, which I have never understood until I used gestures on a touch screen. If your phone doesn't have the speed and screen size for this version, get their non-HD browser. My wife was the one who recommended this to me. Credit where credit is due.
Google Maps -- Yes, your phone probably came with Google Maps installed. But did you know there are updates on the App Market that add features and more maps?
BTW, while Google's GPS navigator is still Beta, it is better than the internal GPS navigation on most phones. Because the phone companies GPS needs to download map data as you are driving, if you enter an area with no cell connection you won't get an update even though GPS is working. Google Maps caches the route you are going to take so the maps are there even if there is no Cell tower on the route.
Brightness Toggle Widget -- One way to improve battery life (a big problem on the EVO) is by turning your screen brightness down as much as you can. This widget makes it possible to cycle through the brightness settings without having to find the setting in the Android menus.
No Lock -- Since I work at home, I don't really need the phone to lock every time it goes to sleep. With this widget you can toggle the lock so that when you wake the phone you are on your home page ready to go. No sliding the lock bar to access the phone. Just remember to turn it back on when you are carrying the phone in your pocket.
Google Translate -- Need to translate something on the fly? This app does it amazingly well. You can even speak several languages to the App and it will translate what you say. It can even speak the text back to you in some languages. Kirk and Spock would appreciate this one.
Barcode Scanner -- Who would have thought using your phones camera as a barcode scanner would be useful? But I found you could scan the barcodes on some products around the house, and then find where you can get the best price for that item if you need to buy more. Really handy, but it can be a bit finicky about lighting as it doesn't use the camera's flash LED's.
ASTRO File Manager -- Does what it says, allows you to view your phones file system. You can delete, copy, move, open and even edit most files directly from the SDCard memory. You can even explore the phones root file system, although you need to have root privileges to really cause trouble.
Remember to check out the ASTRO SMB Module which allows you to connect over your WiFi to another computer and copy files to from your Android. Take that iPhone.
Dropbox -- If you are ok with storing data in the cloud, I highly recommend an account on Dropbox. It allows you to have a folder that is shared with any device on the Internet, or you can upload and download files to it via a web browser. This app allows you to access your Dropbox from anywhere on your Android.
Not Call Log -- Ok, this one is a bit hard to explain. If you have HTC Sense when you make a phone call, at the end of the call you are left in the Call Log. There it is easy to accidentally touch a phone number and start another call. With this app installed, whenever a call ends, you will be taken back to the screen of your choice. It saves accidentally dialing people. Dunno if it is the same for MotoBlur devices or Nexus.
TiVoRemote -- Ok, this is convergence of technology. If you have a Series 3 or later TiVo, you can set it up to allow remote control over the network. With this App you can use your Android to remote control your TiVo from anywhere inside the WiFi network. It is the only app here that I recommend that is not free. But at $0.99 I was very happy to have it, although it seems to lag at times.
Swype (Beta) -- Last but not at all least is this great keyboard replacement for the Android soft keyboard. It is nearly impossible to describe how effective Swype is. With it I can type at nearly an order of magnitude faster on my EVO than I could with the normal tap-tap-tap action. With Swype, you literally swipe your finger over the keys for a word and it does the rest. It has to be used to believe it.
I understand Swype is a standard feature of some Droids. The company is offering a limited time beta sign up so I recommend you see about getting it if you can, even if you decide not to use it. They claim that the beta will not end anytime soon. They want people to test the software on a wide range of Android devices. So hopefully that means if the beta ever does end, we will be able to purchase it.
Hope I didn't bore anyone. Let me know what you are using!