Each story is accompanied by an essay/introduction (written by the author, where possible). The book's organization seems roughly chronological, but I've organized my discussion for ease of reference. Most of the stories first saw print in magazines, the oldest in 1919, the newest in 1997.
Despite the cover blurb's description of the writers as "who was and is who", my reaction to some of the authors on this list was simply: who? The closing "about the authors" is recommended for that question.
Asaro, Catherine: "Dance in Blue" (from CHRISTMAS FOREVER, 1993) is an exercise Bridget (the narrator, a professional dancer) performs under stress. Being trapped inside her missing boyfriend's estate over the holidays with his son and the holograms from which Sadji made his fortune *is* stressful...Nice touch: Sadji isn't the inventor, but the investor who predicted which firms would make the technology pay off. Apart from the obvious mystery, see if you can spot the true purpose(s) of each hologram encountered.
Baxter, Stephen: Other species, being far less technologically advanced, jump at the chance to rifle through the equivalent of Xeelee garbage dumps for artefacts, such as "The Xeelee Flower" (1987). The narrator tells the tale of how scavenging for ET employers on an ex-Xeelee world (racing a supernova) led to his current retirement.
Bujold, Lois McMaster: "Barter" (1985) A stranger requests "all your ammonia" from a young mother who just wants an off-switch for her kids (this being a Saturday morning). "Ah, biostasis field...have lots of spares." Down-side? Where? :)
Burstein, Michael A.: The "TeleAbsence" (1995) of one kid at a private virtual school gives the protagonist a chance to sneak in and experience proper education in another identity.
Card, Orson Scott: "Ender's Game" (1977) The genesis of the novel (although when I first read it, this short story was titled "Ender's War"). In this version, neither Ender's early childhood nor his personal troubles are considered. The enemy and supporting characters are undeveloped (exception: Bean). The accompanying essay should be read with Card's book HOW TO WRITE SCIENCE FICTION if you're interested in analyzing the story's development.
Clarke, Arthur C.: "Loophole" (1946) Epistolary style, mostly letters between Mars' president and chief scientist about the threat of Earth's development of nuclear weapons coupled with space exploration.
Clement, Hal: "Proof" (1942) written as a discussion between members of species that evolved within stars; matter, of course, could never give rise to life...
Czerneda, Julie E.: "First Contact Inc." (from FIRST CONTACT, 1997) developed a computer simulation of first alien contact from military software to a game; the first few scenarios and feedback lead to some oddly specific user requirements trickling in.
de Camp, L. Sprague: "The Isolinguals" (1937) are apparently random victims of a peculiar condition: each convinced that he or she is someone from the past dumped into a strange world. But how could insanity convey a complete knowledge of the language and culture of the alternate personality? Resolution is rushed.
Leinster, Murray: "The Runaway Skyscraper" (1919) An ISLAND IN THE SEA OF TIME-type story: the Metropolitan Tower in New York City mysteriously slides back in time several centuries. Pretty good; immediate concern for resources (food supplies at a late-afternoon low; limited fuel for generator), some allowance for structural damage to the building. Some pseudo-science, but not necessarily from characters who know what they're talking about; imagery like that of THE TIME MACHINE (1960).
Malzberg, Barry N.: "We're Coming Through the Window" (1967) is a letter to the editor of the magazine that accepted it. The correspondent, strapped for cash after too much messing around with a time machine, offers his story in exchange for help.
Martin, George R.R.: "The Hero" (1971) hails from a high-gravity planet devoted to turning out men who spend their lives as front-line soldiers. But Kagen wants to retire to Earth, not Wellington, and see what he's been fighting for all these years...
McCaffrey, Anne: "Freedom of the Race" (1953) A Mars-needs-women post-Earth-conquest story, involving an unusual way of fighting back.
McDevitt, Jack: Hank, a postman lacking self-confidence, experiences "The Emerson Effect" (1981) when an autographed copy turns up in the mail addressed only to 'Henry'. Hank doesn't just become familiar with Emerson's words, but begins waking up in odd situations in the middle of the night, and having to work his way out of them. Motivation...
Oltion, Jerry: "Much Ado About Nothing" (1982) is a first-contact story, but from the viewpoint of an engineer aboard a ship that's just discovered Earth (which to his people seems to have a catastrophically big moon and large axial tilt). Lots of emphasis on avoiding contaminating/being contaminated by the alien ecology, all the while knowing that the engineer isn't well-educated in biology...
Waldrop, Howard: "Lunchbox" (1972) What if the Viking lander happened to land in the equivalent of somebody's livestock pen - but the Martian beings' sensory equipment was completely different from that of Earth animals?
Wolfe, Gene: "The Dead Man" (1965) must fetch water from the river (early, to avoid chaffing by the neighbours for doing womens' work). But the crocodile that bit his wife is still around...