(Not sure if this is the right forum, but it came up during a Scrabble game)
Is there any group of four letters that anagram into more English words than OPST?
(5: opts, post, pots, stop, tops)
6: opts, post, pots, stop, tops, spot
Assuming that is first, is this second? - nips pins snip pins
AEST has five or six depending on how strict you are:
east, eats, sate, seat, teas, and possibly tase
A letter combination that arguably has seven:
ARES – plural of are (the unit of area most known when prefixed by hect)
ARSE – vulgar slang for “buttocks”
EARS – organs of hearing
ERAS – historic periods
RASE – variant of raze (to demolish, as a building)
SEAR – to burn
SERA – plural of serum, watery bodily fluid
Given that the theoretical maximum would be 24, I’d be highly surprised if the record were as low as seven.
+spin
[spoiler]A small program working from a large word list gives me 7 as the max. The top contenders (with 5 or more words):
7: sera, rase, arse, sear, eras, ares, ears
6: stop, tops, pots, opts, spot, post
5: tsar, star, tars, rats, arts
5: soph, posh, shop, hosp, hops
5: vile, live, levi, veil, evil
5: sore, rose, roes, ores, eros
5: twas, wats, taws, swat, wast
5: vela, leva, vale, lave, veal
5: meta, tame, mate, team, meat
5: lira, rial, rail, liar, lair
5: trap, tarp, prat, rapt, part
5: rape, pare, reap, pear, aper
5: sure, ruse, user, suer, rues
5: sate, teas, eats, seat, east
5: sole, sloe, lose, oles, leos
Sternvogel wins, it seems.
[/spoiler]
And for completeness, the best combinations by letter count:
[spoiler]1 (100.0%): a
2 (100.0%): ah, ha
4 (66.7%): ate, eat, eta, tea
7 (29.2%): ares, arse, ears, eras, rase, sear, sera
10 (8.3%): apers, apres, asper, pares, parse, pears, rapes, reaps, spare, spear
9 (1.3%): capers, casper, crapes, escarp, pacers, parsec, recaps, scrape, spacer
6 (0.1%): enviers, inverse, veiners, veneris, venires, versine
6 (0.0%): alerting, altering, integral, relating, tanglier, triangle
4 (0.0%): erections, neoterics, resection, secretion
4 (0.0%): discounter, introduces, rediscount, reductions
3 (0.0%): activations, cavitations, vacationist
2 (0.0%): broadcasters, rebroadcasts
2 (0.0%): impersonating, impregnations
2 (0.0%): conservational, conversational
2 (0.0%): radiotelegraphy, teleradiography
2 (0.0%): microphotography, photomicrography
2 (0.0%): microphotographic, photomicrographic
1 (0.0%): unconstitutionally
1 (0.0%): antiparliamentarian
1 (0.0%): physiopathologically
1 (0.0%): microradiographically
1 (0.0%): electroencephalography
1 (0.0%): disestablismentarianism
1 (0.0%): antidisestablishmentarian
1 (0.0%): antidisestablishmentarianism
Fraction of total permutation count is in parens.
[/spoiler]
Can we allow Esra? That would make 8.
Excellent! I will amaze the rest at our next games get together. 
And kudos to Dr, Strangelove for nailing it down. The five and six letter results are especially nice.
Coincidence that Dr. Strangelove is an anagram of Rad Sternvogel ;)?
ATES
EAST
EATS
ETAS
SATE
SEAT
SETA
TASE
TEAS
Reference: Official Scrabble Players Dictionary
Two letter words WITH 100%:
AA
AB, BA
AD, DA
AH, HA
AL, LA
AM, MA
AN, NA
AT, TA
AY, YA
DE, ED
DO, OD
EF, FE
EH, HE
EM, ME
EN, NE
ER, RE
HO, OH
IT, TI
MM
MO, OM
MU, UM
NO, ON
NU, UN
OP, PO
OW, WO
OY, YO
Three letters with 100%:
EEW, EWE, WEE
HOO, OHO, OOH
MMM
Three letters with 83.3%:
ATE, EAT, ETA, TAE, TEA
Source: Official Scrabble Players Dictionary