As Playboy entered its fourth decade of keeping Hugh Hefner in blondes who were otherwise out of his league, the magazine faced its greatest challenge ever: widely available pornography. Over the next decade, Playboy would go head-to-head with the Internet and its rampant free nude galleries and full-length videos and come out the loser by the end of 1999, when was first mentioned on the magazine's cover.

The decade would be a trying run for the previously indestructible publication, with each issue focused on trying to figure out how to keep an audience that was growing older and, well, less sophisticated.

As with the '70s and '80s, the first year of this new decade didn't go according to plan. January featured Joan Severance, a "sizzling Hollywood newcomer" who promptly vanished into obscurity. A woman named "Bonga" highlighted the dud of a portfolio on Russia's many legendary beauties. Donald Trump played pocket pool on the cover of the March issue and the rest of the year wasn't any better.

Except for July 1990, that is. A young actress named Sharon Stone had just caught the attention of Hollywood after appearing in "Total Recall." A year later, she would become the top sex symbol of the decade, literally overnight, thanks to the blockbuster opening of "Basic Instinct." Sharp-eyed Playboy readers got a glimpse of her much-discussed body parts in this issue, a real high point in a somewhat lackluster decade.

Despite featuring Latoya Jackson and Pamela Anderson in ridiculous outfits on two separate front pages, the Playboy covers in 1991 were a vast improvement over the previous year's. January 1991 kicked things off right with Miss Ohio '90, who wore her sash over her naked breast -- now why didn't they think of that before?
Julie Clarke became the object of our pre-adolescent fantasies by squatting down for the April 1991 cover in a pair of rollerblades. Seeing this now, how come there isn't more rollerblading porn? We might even pay good money for that.

Shane and Sia Barbi, the Barbi twins, posed for the September 1991 issue with their "twins" barely held together by a skimpy bikini. This cover needs no additional comment. When Playboy's on a roll, you have to just sit back and enjoy the show.

Uma Thorensen, Anna Keller, Hilgar Oblief, Eva Jacobsen, Ulla Swensen are the Swedish Bikini Team and the January 1992 cover girls. What is the Swedish Bikini Team, you ask? How are we supposed to know? Now, move along, we have some staring to do here.

1993 once again proved that Playboy was far from dead, with three covers that showed they still had plenty to offer. The first was Mimi Rogers' eye-popping display for March 1993, with those two groping gloves that we wish belonged to us.

The actress was then between careers; she had just broken up with Tom Cruise and was headed toward future success as a competitive poker player. Thank God she needed money at this point, or we may never have seen her glorious boobs, however covered they are here.

Just look at what Playboy packed into their June 1993 issue: "Profile of Nintendo President, Hiroshi Yamauchi ... Golf Carts of the Third Reich; articles: Cash and Commies by Lewis Grossberger; The Thinking Man's Guide to Marriage by Denis Boyles; Of Lust and Arms by William Broyles Jr.; Cindy Crawford and Claudia Schiffer modeling lingerie in the 'Grapevine' segment."

Of course, that description by DT Magazine missed the most important part: the presence of Playmate of the Year Anna Nicole Smith. The cover features Anna Nicole, yet she was already so well-known that she didn't need a name mention or a color print to sell assloads of copies. She was already a legend, a candle burning in the wind ... or whatever.

No, you're not looking at a mirage, example of trick photography, or a bunch of sexy robots from the future. These are Marilise, Lilian, and Renata -- the Porto Sisters, hailing from Tucunduva, Brazil, where they were born on March 1, 1974, making them probably still 18 at the time of their shoot.

Are you in love with them yet, as we are? It's a damn shame Vivid Entertainment wasn't around to offer them each a million bucks for a porn shoot, but at least back issues of the November 1993 Playboy still pop up on eBay from time to time, and that might be good enough.

While 1994 may be one of the best years in the history of Playboy covers, with appearances by Pamela Anderson, Jenny McCarthy, Bo Derek, Patti Davis (Reagan) and Elle Macpherson, it's March 1994 that really had us rejoicing. It takes us back to the days of 90210, when Shannon Doherty was the hottest mean girl in the country -- oh, and she also posed for a "safe sex" pictorial with the future first lady of France. How hot is that?

After two bonanza years in a row, Playboy settled into its old routines of making people like Drew Barrymore look somehow unappealing on its covers. Not so with Shelly Jones, the cover girl for the August 1995 edition of the men's rag. Radio may be dead, but something in our pants sprang to life at the site of Jones in that Andrews sisters-inspired get-up -- why can't this fashion choice come back instead of big sunglasses?

Nothing that year could ever hope to compete with the cover for the March 1996 issue of Playboy -- certainly not anything else the magazine put out that year. (One caveat: we will never complain about seeing Jenny McCarthy butt naked when we open the mailbox.)

Remember, kids, this photo of Amara Dunae was taken years before Britney Spears was even old enough to rock a schoolgirl outfit and get away with that jailbait imagery. Dunae, by the way, recently started modeling again -- the front page of her Web site has some sizzling NSFW photos that put anything Spears has ever done to shame.

21-year-old Newfoundland native Danielle House is the star of Playboy's boner-inducing December 1997 issue. House had recently been stripped (heh heh) of her title as Miss Canada International for landing a nasty right-hook on her ex-boyfriend's new ladyfriend.

While it may not have been the best idea for Playboy to make punny jokes off of the incident, the mixture of princess (her tiara) and devil (crazy exes are not to be trifled with) still gets us going almost 12 years later.

The naked pregnant celebrity magazine cover craze of the early '90s had long passed by the time actress Lisa Rinna posed in a sweater for the September 1998 Playboy. Oh, those swelling nipples ... and that swelling belly, sadly obscured here. If only she had let it all hang out after giving birth, too, we might not have had her unfortunate Playboy shoot from last year, in which ... wow, yeah, plastic surgery really sucks.

Playboy ended the '90s on the right note -- with a solid, entirely consistent year featuring a January cover made up of covers from the past set against a Marilyn Monroe hologram, a Pamela Anderson cover that finally looks hot, a "girls of Kiss" cover that looks enjoyably awful and appearances by Charlize Theron, Sable, that chick who played Lara Croft, and Naomi Campbell.

But we'll pick a long-forgotten one that's just plain sexy as hell -- October 1999, led by 20-year-old college student Jennifer Rovero. The artful combination of a closely-trimmed top and precariously-positioned panties -- oh, who are we kidding with this talk of fashion? These pajamas or gym clothes or whatever they are has us all worked up.

More of this, Playboy, more of this...