Google is inviting Gmail users to participate in the testing of new features for the free messaging service.

On Thursday evening, the company introduced Gmail Labs, a new tab on the Gmail Settings page that offers a selection of experimental Gmail features for users to evaluate. Late Thursday or Friday morning, Google expects to post an announcement about Gmail Labs on the Official Gmail Blog.

At a press event Thursday afternoon at Google's Mountain View, Calif., headquarters, Gmail product manager Keith Coleman described the opening of Google Labs as "a big change in the way we do product development here."

Coleman said that Google has a variety of ways to assess user interest in new features for Gmail. Ideas bubble up internally, they get suggested by users, and publications occasionally publish feature wish lists.

Gmail Labs was created out of the desire to get more features to users faster. Google did something similar last October when it launched Google Enterprise Labs to hasten the availability of search innovations for Google's business customers.

In the past, Gmail's new features have been launched internally at Google, where they might be tested for weeks or months before being made publicly available.

"But we actually want to take the next step and let Gmail users help us with that refinement," said Coleman.

Given the extent to which Google relies on measuring user input and interaction to fine-tune its applications, actively soliciting user input to improve Gmail appears to make sense. Having leveraged the wisdom of the crowd to make its search results more relevant, the company sees potential value in the criticism and enthusiasm of the crowd.

As of Thursday evening, Gmail users will have access to new features that have been evaluated only for code stability, not for user interface coherence or product viability.

"There are actually some things in here that we think are bad ideas," Coleman admitted.

But the point is not what Google thinks; it's what users think. The popular features will eventually become part of Gmail. The not-so-popular features won't.

Some of the experimental features will break. Coleman said that when that happens, the hope is that users will click on the feedback link associated with flaky feature, which will take the user to a Google Groups discussion with the engineer responsible. "There's a direct connection with the people who are designing these things," he said.

The initial crop of experimental Gmail features includes: Quick Links, which lets Gmail users bookmark any page view in Gmail; Superstars, which provides a variety of colored stars with graphics for flagging messages in a more meaningful way; and Old Snakey, a snake game that runs inside Gmail.

There's also Pictures In Chat, Fixed Width Font, Custom Keyboard Shortcuts, Mouse Gestures, Signature Tweaks, Random Signature, Custom Date Formats, Muzzle, Hide Unread Counts, and Email Addict.

Email Addict, Coleman explained, provides a link at the top of the main Gmail pane that can be used to voluntarily lock oneself out of one's Gmail for 15 minutes, in order to get some real work done.

Coleman said that the Gmail team is looking at the possibility of allowing users to actually develop Gmail features or add-ons, but isn't ready to announce anything.

Google, said Coleman, is trying to be the opposite of lumbering companies that take months or years to get anything done. "We want to build basically the model of a 100 million user startup," he said, "where people can do whatever they want, as they would with a nimble startup, but can actually have the reach of a large popular product like Gmail."