A widget that shows Google+ Activities. Specify the G+ id and the API Key, and place it on your blog template, and the widget does the rest.
You need an API key from Google so that the requests that your wordpress page sends to Google, will be authorized and allowed. Every time the page loads, it sends out a request to Google, and gets the list of activities. Google wants to know who's asking for this information, and the API key lets them track that.
To get an API Key, you need to visit. https://code.google.com/apis/console and click "API Access" on the right-hand-=side navigation menu.
Copy and paste the API Key to the appropriate place in the Widget configuration menu.
No. The API key is free to get; you don't even need to ask for it. In fact Google will just display the API key when you login to the API Console. I don't speak for Google, but it seems to me they use the key only for tracking purposes.
Google may throttle the level of requests if you use this plugin on a heavily loaded site. In that case you may need to use OAuth2.0, which I have not yet builtin to the plugin. But I could be convinced, for the right price. ;)
You can get it by examining a particular URL when you login to Google+.
First, you need to be on Google+. Go to https://plus.google.com and login or sign up. It's free to signup. (But you already knew that, because you are on Google+, otherwise why would you want a G+ widget?)
Then, click the link for your profile. It will go to a URL like this:
Your id is the long string of digits in the middle there.
No, I haven't built that capability into this simple plugin, just yet. Let me know if you have strong requirements in this area.
You can "manually" apply css styling to the list. The css class name used for the UL that holds the list of Google+ activities is 'gplus'.
Yes. You can set the cache lifetime in the widgets panel of the admin UI.
The term "cache lifetime" refers to the time period that the widget will re-use results from the Google+ Activity query. When rendering itself on a page, if the Widget has requested and received a list of activities from Google within the cache lifetime (say, within the past 10 minutes), then the widget will re-use those results. If the Widget has no saved results, or the saved results are older than the configured cache lifetime, then the widget will send a new request to Google to get the information.