Office 365's marketplace mixes tools and services, with support for third-party solution providers.
You use the domain federation tools in Office 365 to connect Lync to public IM services.
You'll need to enable domain federation to connect Lync to other businesses: we'd recommend connecting only to whitelisted domains.
The Office 365 SharePoint service is just like any on-premises SharePoint installation — minus a handful of features.
Office 365 includes self-service tools so users can work with their own mail accounts, seeing just how much space they have left, and how to connect other mail clients to their accounts.
Log on as a user, and you'll see a basic start page that gives quick access to web mail and SharePoint team sites, as well as download links for applications. You'll also find help in setting up a desktop PC to work with the Office 365 service.
If you've used Outlook Web Apps with on-premises Exchange, then you'll find the online OWA that's part of Office 365 very familiar.
Exchange Online gives you the tools to take control of mail flow inside your business, managing server rules. You can also use Forefront Online Protection to add additional anti-spam and anti-malware controls.
Regulated industries need to be able to prove that they're working within the appropriate framework. You can use Exchange Online's auditing tools to provide regular reports, online or via email.
Office 365's Exchange Online has tools for working with user mailboxes (and batch-importing users from your directory if you're setting up mail from scratch).