As promised, here is a list of great Android apps that I have on my HTC desire mobile phone (I won’t cover games, as everyone has different opinions on games):

Note: I’m not a big facebook or twitter user, so I won’t cover the built-in and downloadable apps for social networking, but I’m sure there are many to choose from.

• Catch (catch.com). I started looking for a notes app on my iphone (before I got my Android), and eventually settled on catch. I was mainly after an app that would save notes to “the cloud”, in case my phone broke down… I would have preferred an app that saved the notes to my gmail account, but since Catch is easy, very quick, flexible (I can also save sound recordings and photos), and works on a PC, iphone, and Android, then its my best choice.
• Firefox. I initially resisted putting Firefox on Android, but once I started using Firefox sync, I decided to try it. The biggest problem I find is that its much slower to load (compared to the built-in webkit browser). However, once you get used to it (it has slide-out bars on the right and left), its actually very powerful and flexible.
• Barcode scanner. Although I don’t use it much, its great to be able to whip out my phone and scan a 1D or 2D (QR-code) barcode. Its simple, and it works.
• Clinometer. This uses the accelerometer to measure the inclination of the phone in any direction. You can also change the skin to suit your needs.
• Compass. Great for finding your cardinal directions. Like with any compass, it can get confused it you are in your car, or near most metals. But if you get lost in the South American rainforest, then you can be sure of heading in the right direction (at least for 2 hours, after which the phone batteries will run out!)
• Elixir. This is great for tech-heads like me, where you can get all sorts of nitty-gritty information about your phone (free RAM, CPU speed, CPU usage, battery temperature, etc). But not very useful for average people.
• Gmail (as well as Google contacts and Google calendar). This is probably my most useful set of applications (by far!). If you run a business and you deal with customers on a daily basis and you travel a bit, then this is essential for keeping your office with you at all times. Even if your phone gets destroyed, you can buy another Android or iphone, and check your mail, get customer details, and check your appointments, without missing a beat. Just make sure you use gmails imap feature, and you will never care about breaking your phone again.
• Handycalc. Very powerful calculator, with extra add-ons for currency conversion, unit conversion, function graphing. Lots of nice functions in the one app.
• Dropbox. This is in a similar category to the Google apps, in that you can choose what files to save to the “cloud”. So I use it for anything that I need to access from remote locations, or if I need to transfer data to someone else.
• Keepassdroid. I have a huge number of passwords that I need to remember. Everyone has their own way of dealing with the internets password blowout. Some will try to use the same password everywhere (doesn’t always work, and you are putting all your eggs in one basket), others will write them down in a book. There might be better password safes out there, but I like keepass, as its open-source, seems to run on just about any device, and best of all, I put the database into dropbox, so I’ve always got the most recent set of passwords, without needing to copy the master password file around!
• Sms backup+. After having lost all my saved SMS messages when my last smartphone suddenly broke down, I decided to look for something that would backup my SMS messages. Althought there is nothing like it on the iphone yet (!), I found SMS Backup+ will backup all SMS messages (incoming and outgoing), and also backup my call log (incoming, outgoing, missed calls, etc), and best of all: it saves the data to gmail, so I can read my sms messages from my PC!
• SoundHound. To me, this is a novelty, but it has been nice to hear a song, find out what its called, get the lyrics, and then sing along (despite most people wishing I didn’t sing!). I also tried Shazam, but since it cannot be moved to the phones SD card … it then ends up using too much of my phones limited internal memory…
• Where’s my droid. Thankfully I’ve never needed to use this for “real”, but it will allow you to send an SMS message to your phone, and it will report back either its GPS coordinates (assuming GPS is on, and the phone has a GPS lock… so that part won’t work indoors)… or it will report an approximate location based on the triangulation data from the phones cellular phone network (much more reliable, but much less accurate). Its good to keep this as a backup if you lose your phone (or it gets stolen).
• WiFi Analyser. Its a great visual aid for diagnosing WiFi signal problems, as it shows any WiFi signals it can detect, and can do it in real-time in an easy to read graphical format… Its become an essential tool in my line of work!