If your company has made a commitment to using Google Apps, it may be able to drive more value out of that decision by adopting one of the many related applications featured in the Google Apps Marketplace.
If the sheer variety of choices overwhelm you, you could start by checking out the ones that have been installed most often by other businesses (a list that appears in the far righthand side of your browser screen). Most of them are for small or midsize organizations (although a couple appear to be meant more for large accounts).
For the purposes of shorthand, here is the top 10 list in descending order (as of the afternoon of March 28, 2013):
Mavenlink: A workforce and project management system that shows time sheets, budgets and costs related to ongoing projects, accounts receivable aging reeports and other information that will help with resource utilization and planning.
MailChimp: A newsletter service that can be integrated with a bunch of other popular small business cloud apps, including Rapportive, Batchbook CRM, Zendesk and Freshbooks. It also connects with e-commerce software including Shopify and Magento.
FlashPanel: Management and security capabilities, including the ability to manage passwords, control user access, manage email usage and consumption, or create (and delete) shared contacts.
Gantter Project: An application for handling scheduling of complex projects, which integrates with Google Drive for sharing and collaboration. It can import files from Microsoft Project.
Zoho CRM: As with the other CRM tools mentioned, this service is for tracking leads and customer prospects. But it can also be used for customer support management and marketing automation.
Do by Salesforce: A projects and tasks manager; you can share items with people on your Google Contacts list.
Draw.io: An app for producing graphical diagrams using predefined objects. (The pricing model changes on April 1, 2013, so it should be interesting to see if this software retains is popularity.)
Accounting tools by Wave: A small-business accounting system that includes invoicing and reporting features.
What other Google Apps ecosystem software do you find useful? Leave us some ideas in the comment thread.