List of yaku

1 Han closed only

Tsumo 「門前清自摸和」 You draw a winning tile from the wall.
Riichi 「立直」 You declare that you're one tile away from a finished hand. This locks your hand down.
Ippatsu 「一発」 This is awarded when you win on the first four turns after declaring Reach. A Pon/Chi/Kan from another player cancels Ippatsu.
Pinfu 「平和」 Your hand is composed of 4 Chis and a valueless pair. The winning tile is required to finish a two-sided wait. "The basic hand."
Iipeiko 「一盃口」 A hand with two identical Chi's.

Haitei 「海底撈月」 The hand is completed with the last tile on the wall.
Hotei 「河底撈魚」 The hand is completed with another player's last discard.
Rinshan Kaihou 「嶺上開花」 The hand is completed with a tile from the dead wall.
Chankan 「搶槓」 The winning tile for a hand is called on another player's Kan. Essentially, the tile needed to complete a Kan is stolen to complete a winning hand.
Tanyao 「断幺九」 A hand composed of only inside (numbers 2-8) tiles[/spoiler]

Double Richi 「ダブルリーチ」 Richi declared on the first round. Closed only.
Chi Toitsu 「七対子」 Hand with seven different pairs. Closed only.
Chanta 「全帯幺九」 All sets contain terminals or honours.
Sanshiki / Sanshoku 「三色同順」 A hand with three Chi's of the same numerical sequence, one of each suit.
Ittsu 「一通貫」 A hand with a set 1 through 9 of a single suit.
Toi Toi 「対々」 All Pons hand.
San an kou 「三暗刻」3 Pons concealed
Sanshoku Douko 「三色同刻」 Hand with 3 Pons of the same "number".
San Kansu 「三槓子」 Hand with three Kans.[/spoiler]

Honitsu 「混一色」 Hand with tiles from only one of the three suits, in combination with honours.
Ryanpeiko 「二盃口」 Two sets of "Iipeiko". Closed only.
Junchan 「純全帯么」 All sets contain at least one terminal.

Honroto Toiho 「混老頭対々和」 All terminals and honors.
Shousangen 「小三元」 The hand contains two sets of 3 dragon tiles and a pair of the third dragon tiles.

These actually count as two. But they're 4 due to the additional yaku of Toi Toi and 2x Yakuhai respectively.

This is the only yaku set at 6 han, where the number drops to 5 han when opened.

Chinitsu 「清一色」 Hand composed entirely of tiles from only one of the three suits.

Kokushi Muso 「国士無双」 Hand with one of each of the 13 different terminal and honour tiles plus one extra terminal or honour tile. (For some rules, Double Yakuman for a 13-wait set)
Chinroto 「清老頭」 All terminals
Daisangen 「大三元」 A hand with three Pon's or Kan's sets of the three Dragons.
Su Anko 「四暗刻」 A concealed hand with four concealed Pon's. (Tsumo only and depending on rules, Double Yakuman if win on a pair wait)
Su Kantsu「四槓子」 A hand with four Kan's.
Shosushi 「小四喜」 A hand with three Pon's/Kan's sets of winds of and a pair of winds.
Daisushi 「大四喜」 A hand with four Pon's/Kan's of winds. (Double Yakuman, depending on the rules)
Churen Poto 「九連宝燈」 A hand consisting of the tiles 1112345678999 in the same suit plus any one extra tile of the same suit.
Ryu Iso 「緑一色」 A Hand composed entirely of green tiles: 2, 3, 4, 6 and 8 Sou and Hatsu.
Tsu Iso 「字一色」 A hand composed entirely of honour tiles.

Tenhou 「天和」 The dealer wins on his first turn.
Chihou 「地和」 A non-dealer player wins on a draw tile at the first round.
Renhou 「人和」 A non-dealer player wins on a discard at the first round. Variance may set this to mangan, or not used at all.

This yaku does not specifically deal with a player's hand, but rather the player's discards. By default, this hand is set to mangan.

Nagashi Mangan 「流し満貫」 All the discards are terminals or honors. Plus, none of the discards were called pon or chi to form melds.[/spoiler]