They get together every Friday, but don't call it a club. You'll probably meet people who can further your career, but don't call it a networking group. You might even find romance, but don't call it a singles party. In fact, don't call it anything. Just follow their simple slogan, attached at the end of every e-mail invitation: "Giddy Up. Pass it on. See you there."

For lack of a better description, the 501 "club" is an informal and free happy hour that meets each Friday at, you guessed it, 5:01 p.m. It's the brainchild of Toby and Mel Richer, who loosely borrowed the concept from a group they found in Chicago. There's not too much to the concept: 501 doesn't have a president or a set location. There aren't many rules, either. One is the venue for the meetings are selected by a "picker," who is chosen by last week's picker.

That process is somewhat unscientific. Says Toby, "It's evolved into buy the picker a lot of drinks, and he or she will make you the picker."

Another rule is the venue can't repeat. Recent locations include Trocadero, County Claire, Vox, Hi Hat, Flannery's, Dino's, Club Havana, Von Trier, Summerfest and The Knick.

Like the cocktails, as dusk turns into evening, everything else flows surprisingly naturally from there.

"It has a life of its own," says Mel, who works in sales. "We're not really in charge anymore, but we do take a lot of pride in seeing it off the ground."

Numbers are growing for this inconspicuous gathering, which held its first event in May. Since then, 40 or more young professionals each week have turned out for the laid-back happy hours. According to Mel, most of the group ranges in age from about 25-35, but younger and older people show up, too. Many of them are single, but it's certainly not a requirement. You can talk about work if you want, but the focus is more about meeting new people and enjoying a cocktail after a long week.

"The point was never to be about networking, but it became a byproduct," says Toby, a Milwaukee attorney. "You end up talking about what you do, and people make connections from that."

You may also find romance at the parties, which tend to run late into the night. A group of fun-loving young people meeting for happy hour is, after all, a recipe for love.

"There's a fantastic couple that met at 501. The guy was being fought over by a bunch of girls, and one won," says Mel.

And talk about having the opportunity to make a first impression, then follow up later. "You can see the same girl week after week," adds Toby.

Mel says she hopes the group continues to grow, especially with new people. "I have a 501 rule that I don't sit. I totally work the room."

The club has certainly boosted the social life of Mel and Toby, who moved to Milwaukee last year. Toby, who grew up in Milwaukee, finds the group is a great way to do something a little out of the ordinary.

"I don't think Milwaukee is always the easiest place for people to move into town and meet new people. There's not really a problem with that in 501."

Since there are no members, no fees or nothing particularly official about 501, the only way to find out about the upcoming week's party is by e-mail.

"One bar owner asked me how he can get the list, but there isn't a master list," says Mel. "Everyone has their own list."

And each invitation is more creative than the last, as the picker tries to put a creative spin on the e-mail. One week, the invitation was a variation on the "Brady Bunch" theme song.

Typically, you'd have to ask another person on the list to put you on it; Toby made it easier by registering for a free OnMilwaukee.com e-mail account at 501mke@onmilwaukee.com. If you're interested in finding out about the next venue, e-mail him and ask to be included.