We're a small team of a few developers looking for a tool that we can use to plan software development and help us keep on track. We already have meetings set up in Google Calendar (we use Google Apps). Is there a tool that is simple to use and doesn't slow us down and integrates well with Google Calendar?
We looked at omniplan (we use Mac OS X) and like its simplicity and leveling feature, but it doesn't import any calendar feeds to keep in mind time spent in meetings.
It's very extensible and there are many plugins available. I'm not sure whether coogle cal. can be integrated very well.
If are small, in the same location and like Agile, use Pivotal (free-hosted).
If you have products, bugs, releases, and sort of things to keep track of, JIRA (or BugZilla), and link it to your SCM (i.e. Subversion).
When in doubt, start with a Wiki (MediaWiki or XWiki are great). You won't regret it (and even if you add later more tools, I bet you will still keep the Wiki).
I am not sure how it integrates with Google Calendar, but we are using VisionProject to manage our whole development process, including the activities after release, such as bug tracking, client support, etc. This is also brilliant for version management of the product.