For unlimited Madden Cards
Create two profiles Using one as your main one and on the other you just have to get 100 tokens. After you get the 100 tokens you go to the Madden cards option and buy a pack. Then you go to the trade cards option and trade all of the cards from that profile to your main one. After you've done that you exit the madden cards screen, when it asks if you want to save profiles you click no.
Now you go to the memory card option and save ONLY your main profile. Turn the game off and back on and the other profile still has 100 tokens and you have the cards that you traded to yourself. I know it's not really a cheat, but hey, it works.

Fat Man
Hold circle and press L1.

Change Players Attributes
Go to the main roster menu, then go to the edit player category and select a player of you choice. Move the curser right to the speed category and then hit the X button twice. This will allow you not only to change players speed, but also will allow you to change all of their other attributes.

Ultra Barry Sanders Blows Pass Everyone
Square and circle hold down and L1 and R2.

Team Unlocked - Secret Code
All Giants - Biggiants
All 49ers - Goldniners
All Jets - Greenjets
All Bears - Brownbears
All Lions - Silverlions
All Bills - Bluebills
All Packers - Yellowpacks
All Broncos - Buckingbroncos
All Panthers - Bigcats
All Chargers - Bluechargerst
All Patriots - Redpats
All Chiefs - Redchiefs
All Raiders - Silverraids
All Colts - Whitecolts
All Rams - Goldramst
All Cowboys - Bluecowboys
All Redskins - Redindianst
All Dolphins - Aquafins
All Saints - Marchingins
All Eagles - Greeneagles
All Steelers - Blacksteels
All Falcons - Blackfalcons
All Vikings - Conquerd

Team Unlocked - Secret Code
1957 49ers team - Goldrush
1977 Raiders - Theghosts
1957 Lions team - Lionpower
1978 Dolphins - Cannedtuna
1958 Colts team - Stables
1978 Chargers team - Roller
1958 Giants team - Jollygreen
1978 Oilers team - Earl
1960 Eagles - Greenwingst
1978 Raiders team - Holy
1962 Oilers team - Therewasaman
1978 Steelers team - Dynasty
1962 Texans team - Getem
1979 Cowboys team - Comeback
1966 Chiefs team - Megiveyou
1979 Bucaneers - Pirates
1966 Cowboys team - Whoshotjr
1981 49ers team - Thecatch
1966 Packers team - Champs
1981 Bengals team - Tigers
1967 Cowboys team - Tundra
1981 Chargers team - Ironman
1967 Packers team - Snowplow
1981 Cowboys team - Nochance
1967 Rams team - Blitzer
1983 Raiders - Homesick
1968 Colts team - Shocker
1984 Dolphins team - Dantheman
1968 Raiders team - Heidi
1985 Bears team - Upset
1968 Jets team - Tvtimeout
1985 Falcons team - Flyaway
1969 Chiefs team - Nofluke
1985 Patriots team - Blowout
1969 Vikings - Allflukea
1986 Broncos team - Thedrive
1970 Jets - Damnyankeest
1988 Bengals - Nohopea
1970 Browns team - Mnf
1989 Broncos team - Crushed
1970 Vikings - Peopleeater
1990 Raiders - Oneeyed
1971 Chiefs team - Overtime
1990 Bills team - Wideright
1971 Cowboys - Starsa
1991 Falcons team - Neonlights
1971 Dolphins - Longestgame
1991 Lions - Toomuch
1972 Raiders - Sourd
1992 Cowboys - Howboutem
1972 Colts team - Airshow
1992 Bills team - Comebackkid
1972 Dolphins team - Perfect
1993 Bills team - Notagain
1972 Steelers team - Lucky
1994 49ers - Bythebays
1973 Bengals - Junglecats
1994 Broncos - Oucha
1974 Dolphins - Defenderst
1994 Chargers team - Charge
1974 Raiders - Struggles
1996 Packers team - Almost
1974 Vikings - Tarka
1996 Panthers team - Defense
1974 Steelers team - Steelcurtain
1998 49ers team - Thecatchtwo
1975 Cowboys team - Hailmary
1998 Packers team - Noluck
1975 Vikings team - Purple
1998 Vikings team - Missedchance
1977 Colts - Ghosttothepost
1999 Rams - Nowhereman
1977 Cowboys - Usateam
1999 Titans - Miracleplays

Unlock Madden Teams
To unlock these All-Madden teams, type in these codes at the 'Secret Codes' Menu.
Team Unlocked Secret Code:
1984 All-Madden team - Madden84
1985 All Madden Team - Mad1985
1986 All-Madden team - 86madden
1987 All Madden Team - 1987mad
1988 All-Madden team - Madden88
1989 All Madden Team - Mad1989
1990 All-Madden team - 90madden
1991 All Madden Team - 1991mad
1992 All-Madden team - Madden92
1993 All Madden Team - Mad1993
1994 All-Madden team - 94madden
1995 All Madden Team - 1995madn
1996 All-Madden team - Madden96
1997 All Madden Team - Mad1997
1998 All-Madden team - 98madden
1999 All Madden Team - 1999mad

Unlock the Mummies Team
To unlock the 'Mummies Team', type in the following code at the 'Secret Codes' Menu: Kingtut.

Touchdown celebrations
Enter one of the following codes after scoring a touchdown:

Hip Thrust: Press L1 + Square.
Jump Spike: Press L1 + Circle.
Say a Prayer: Press L1 + Triangle.
Shoulder Shake: Press L1 + R1.
Slam Dunk: Press L1 + R2.
Spike Football: Press L1 + X.