The Calendar can view sub-calendars for each account you have and you can give each a different color to make it easier to tell apart. You can also disable sub-calendars if they're getting in the way.
The calendar offers day and agenda views too for more comprehensive hour-by-hour browsing of your appointments.
To-dos can be created too. Those can only be synced with Live accounts, and not a Gmail account for example. Each to-do can have a priority reminder, due date and notes. Later, to-do's can be sorted by priority.
The WP calculator is nothing extravagant - it has the simple portrait view of basically all calculators on the planet, while turning it over to landscape reveals the more complex scientific mode.
The alarm app is simple to use and has an iOS-esque interface. You get the alarm time with an on/off switch to the right.
Windows Phone 7.8 provides users with the basics in smartphone organizing but should you need anything more the Marketplace is there too - it offers apps for just about everything - most of which are free.
There's an app called Contacts Transfer (updated with Windows Phone 7.8), which does just that - it pairs with another phone over Bluetooth and leeches out your address book. This makes switching from your old phone to the Nokia Lumia 510 a smooth sailing.
There is the Ringtone Maker too - there you pick a song from your Zune library, choose an interval of up to 30 seconds from anywhere in the song, and tap on Save. Then a ringtone is saved in your library and you can use it from the settings menu.