Having had my Windows Phone 7 for a while now I've come across a number of features that weren't obvious to me from day 1. You may already know some or all of these (I have seen some on other sites) but take a look and see what you think. If you have other tips that you'd like to share let me know.
1. Change picture hub background
The picture hub has a double-width tile on your phone's start screen, and it's surprising how many people don't change the rather bland default photo that you get with a new phone. Changing it is easy: Open the picture hub then press and hold on an area where there is no text - an option will appear to "Change background". Select it, and you can choose the picture you want from you camera roll or saved pictures.
Note that once you've selected the picture (but before you accept it) you can slide it around in the frame to get the fit you want, and even pinch/zoom to hone into a particular area.
If you're feeling reckless select the "Change it for me" option and the phone will select a random picture. Whenever I do this I always seem to end up with an embarrassing picture, but maybe that's just me.
2. Change the lock screen photo
Hopefully everyone knows how to do this but for completeness: Select a photo from within the pictures hub, press the "…" at the bottom right, and choose "Use as wallpaper". Note that like the picture hub background you can slide it around in the frame and pinch/zoom to get the fit you want before you accept it.
3. Forward a Text (SMS) message
Perhaps not as intuitive as it should be, but pretty simple once you know how. To forward a text message just press and hold on it - you'll get the option to "Delete" or "Forward"
4. Precision editing of entered text
If your fingers are of the stubby variety (like mine) you may have trouble selecting the exact position you want to edit in a piece of text. For example, when you're typing an email and notice an error, you might want to position the cursor mid-sentence a few lines up. The easiest way to do this is to press and hold anywhere on the text and a little cursor will appear above your finger. Drag down and position it exactly where you need. In case you were wondering it appears above your finger rather than under it so you can see what you're doing.
5. Viewing a column of text on a web page
When you're viewing a webpage there is often an area of the page with a column of text that you need to read. You can of course zoom in manually but there's a quicker way to get the text zoomed to the right size - just double tap on the text you're interested in and the browser will size it to fit the screen exactly. Double tap again to zoom back out.
6. Saving a photo from a web page
Found a nice picture on a web page you're viewing? Press and hold on it and you'll get the option to either save it to your photo, or share it via email, text, etc.
7. Sharing a web page
Found a web page that might be interesting to someone else? Press the "…" at the bottom right while you're viewing the page and select "Share page"
8. Downloading a song or album in Zune Marketplace
If you have a Zune Pass you can stream just about any song in the Marketplace. But you can also download them your phone for offline listening. To download a song just press and hold on the song title, then select "download". To download the entire album, press and hold on the album title and select "download". The download continues in the background so you don't need to wait on this screen until it completes.
9. Rating and reviewing apps
Tell those developers what you think of their apps: From the start screen swipe right to get the complete app list. Find the app you want to review/rate then press and hold on it. Then select the "rate and review" option.
10. Get a spare battery
Unlike the iPhone most Windows Phones aren't sealed units - you're able to get to the battery. This means that if you buy a spare battery you can effectively get double the usage time from your phone. When the battery runs down, switch off the phone and swap batteries. Within 30 seconds of the phone dying you're back at full charge.
I have the HTC 7 Mozart and have had no problem doing this but I'd be interested in other people's experiences with other phones. On the Mozart you need to hold the camera button in while sliding the back, and the battery then takes seconds to remove. The actual battery is very small and slim, I got the replacement for £20 but you can probably shop around and get it cheaper.
What this means is that I can use the phone the way it's meant to be used: Wireless on, 3G on, location services on, listening to music and playing games, reading books, etc without fear that you're going to end up with a dead phone. In fact, I've thought about getting a second spare which would give me 3 days of pretty heavy use before I need to start charging.
One other thing that may be on your mind: When you remove the battery nothing is lost ie you don't need to reset anything. You just switch the phone back on and it works exactly as it did before you changed batteries.
11. Add LinkedIn messages to the People Hub
The people hub is a great quick way of getting notifications about your friends and contacts - Facebook postings, Windows Live updates, photos that are emailed to you all appear here. To get LinkedIn posts from your contacts to show up here as well, just add LinkedIn to your Windows Live connections. Go to www.live.com, and click the "add" dropdown in the "Messenger social" area and follow the prompts.
And because many people have Twitter joined with their LinkedIn account, you'll get Twitter posts from many of your LinkedIn contacts too.
Note for clarity: Doing this will not sync your LinkedIn contacts with your phone. It will simply show LinkedIn messages in the People Hub alongside things like Facebook and Windows Live updates.
12. Pin web pages to the start screen
lf you regularly visit particular websites you can pin them to your start screen for easy access. Simply visit the site and click the "…" at the bottom right, then choose "pin to start". A tile with a snapshot of the screen will appear on your start screen (and of course you can drag it around to the position you want).
13. Share a photo on Facebook
I'm sure you all know this but I'll mention it just in case because it's a great feature: When you've taken a picture with the camera, you can immediately press the "…" and select "share", then "Upload to Facebook". You can even enter a title for it before it uploads. It means that it takes just seconds to get a photo onto Facebook after you've taken it - assuming that's what you want!
14. Save typing ".co.uk"
The on-screen keyboard often offers a ".com" button when you're typing an email or web address. But what if you're not in the US and you're looking for a .co.uk address? Just press and hold the ".com" button and you'll get a ".co.uk" option.