The next list shows all the documentated Dreamcast UserAgents from the 3 main WebBrowsers: DreamPassport, PlanetWeb and Dreamkey.

Extracted from: JeffMa website

DreamPassport1.0
DreamPassport
SonicPassport

DreamPassport1.01
DreamPassport/1.01
7thFNPASSPORT/1.01
ShutokouPassport/1.01
RealSoundPassport/1.01
Zero3Passport/1.01;custom

DreamPassport2.0
DreamPassport/2.0
DreamPassport/2.0; BANDAI/DCGUNDAM1
DreamPassport/2.0; BOTTOMUP/GOLF_SHIYOUYO 
DreamPassport/2.0; CAPCOM/SF3_W_IMPACT
DreamPassport/2.0; CAPCOM/GIGAWING
DreamPassport/2.0; ECOLE/DeathCrimson2 
DreamPassport/2.0; FROMSOFTWARE/FRAME GRIDE 
DreamPassport/2.0; MASAYA/LangrisserMillennium 
DreamPassport/2.0; MICROCABIN/MARIONETTECOMPANY 
DreamPassport/2.0; NAMCO/SOULCALIBUR
DreamPassport/2.0; NEC HE/SENGOKU TURB 
DreamPassport/2.0; RIVERHILLSOFT/VermilionDesert 
DreamPassport/2.0; SEGA/CHUCHU 
DreamPassport/2.0; SEGA/ONSEN 
DreamPassport/2.0; SEGA/Yakyutuku 
DreamPassport/2.0; TREASURE/BANGAIOH 
DreamPassport/2.0; UEPSystems/CoolboardersBurrrn
DreamPassport/2.0; VIDEOSYSTEM/F1WorldGrandPrix

DreamPassport2.1
DreamPassport/2.1
DreamPassport/2.1; AKICorp/ANIMASTAR 
DreamPassport/2.1; BANDAI/GIHREN 
DreamPassport/2.1; CAPCOM/GUNBIRD2 
DreamPassport/2.1; CAPCOM/MARVELVSCAPCOM2 
DreamPassport/2.1; CAPCOM/SF33rdSTRIKE 
DreamPassport/2.1; CAPCOM/PowerStone2 
DreamPassport/2.1; CARAMELPOT/Golem 
DreamPassport/2.1; Cyberfront/PB4 
DreamPassport/2.1; DaZZ/LakeMastersProDCPlus 
DreamPassport/2.1; ESP/OukaHousin 
DreamPassport/2.1; GAE/Imperial 
DreamPassport/2.1; GENKI/NIUNIU 
DreamPassport/2.1; GENKI/SHUTOKOUBATTLE2 
DreamPassport/2.1; HUDSON/RUNEJADE 
DreamPassport/2.1; KID/MemoriesOff 
DreamPassport/2.1; KID/TREASURE_STRIKE 
DreamPassport/2.1; MICROCABIN/MARI2 
DreamPassport/2.1; NAMCO/Mr.DRILLER 
DreamPassport/2.1; RIVERHILLSOFT/WorldNeverland2TheWakticRepublicOfPlutoStories 
DreamPassport/2.1; SEGA/add-dc 
DreamPassport/2.1; SEGA/DreamFlyer1.0 
DreamPassport/2.1; SEGA/HANACOLA2 
DreamPassport/2.1; SEGA/JETSETRADIODX
DreamPassport/2.1; SEGA/ROOMMANIA203 
DreamPassport/2.1; SEGA/SAKATUKU 
DreamPassport/2.1; SEGA/SAMBA DE AMIGO 
DreamPassport/2.1; SEGA/SegaGT 
DreamPassport/2.1; SEGA/VIRTUAL-ON ORATORIO TANGRAM
DreamPassport/2.1; SEGA/Visualpark 
DreamPassport/2.1; SEGA/Yasobou 
DreamPassport/2.1; SEGA/YASONET 
DreamPassport/2.1; SEGA/ZombieRevenge 
DreamPassport/2.1; SNK/CoolCoolToon 
DreamPassport/2.1; SNK/KOF99EVO 
DreamPassport/2.1; SONICTEAM/PSOBBA 
DreamPassport/2.1; Waka/Otoire

DreamPassport3.0
DreamPassport/3.0
DreamPassport/3.0; ABEL/EXODUSGUILTYNEOS 
DreamPassport/3.0; ABEL/TANTEIDASH 
DreamPassport/3.0; AmusementVision/DAYTONAUSA2001 
DreamPassport/3.0; AQUAPLUS/COMICPARTY 
DreamPassport/3.0; ATMARK/NETVERSUSCHE 
DreamPassport/3.0; ATMARK/NETVERSUSGOM 
DreamPassport/3.0; ATMARK/NETVERSUSHAN 
DreamPassport/3.0; ATMARK/NETVERSUSIGO 
DreamPassport/3.0; ATMARK/NETVERSUSJAN 
DreamPassport/3.0; ATMARK/NETVERSUSREV 
DreamPassport/3.0; ATMARK/NETVERSUSSHO 
DreamPassport/3.0; BANDAI/GUNDAMBATTLEONLINE
DreamPassport/3.0; Bimboosoft/Jd2
DreamPassport/3.0; CAPCOM/BIOHAZARD3 
DreamPassport/3.0; CAPCOM/ELDORADO1 
DreamPassport/3.0; CAPCOM/ELDORADO2 
DreamPassport/3.0; CAPCOM/ELDORADO3 
DreamPassport/3.0; CAPCOM/ELDORADO4 
DreamPassport/3.0; CAPCOM/GUNSPIKE
DreamPassport/3.0; CAPCOM/heavymetal 
DreamPassport/3.0; CAPCOM/MARSMATRIX
DreamPassport/3.0; CAPCOM/MOEROJUSTICEGAKUEN 
DreamPassport/3.0; CAPCOM/R_ZERO3 
DreamPassport/3.0; CAPCOM/Spawn
DreamPassport/3.0; CAPCOM/SSF2XM
DreamPassport/3.0; CAPCOM/VAMPIRE
DreamPassport/3.0; CAPCOM/CAPCOMVSSNK
DreamPassport/3.0; CAPCOM/CAPCOMVSSNKPRO
DreamPassport/3.0; CAPCOM/CAPCOMVSSNK2
DreamPassport/3.0; CAPCOM/GigaWing2
DreamPassport/3.0; CSK/EKEMPODP3
DreamPassport/3.0; CRI/18Wheeler 
DreamPassport/3.0; CRI/AEROI 
DreamPassport/3.0; CRI/AEROFSD
DreamPassport/3.0; CRI/AEROISD
DreamPassport/3.0; CRI/PowerJetRacing2001
DreamPassport/3.0; DATAMPOLYSTAR/HAPPYLESSONFirst
DreamPassport/3.0; GAINAX/TYPINGEKEIKAKU
DreamPassport/3.0; Hitmaker/PowerSmash
DreamPassport/3.0; isao/MyDiGiDiGi
DreamPassport/3.0; isao/MyDiGiPeti
DreamPassport/3.0; isao/MyDiGiRabi
DreamPassport/3.0; isao/MyDiGiPyo
DreamPassport/3.0; MICRONET/MARIONETTE_HANDLER_2
DreamPassport/3.0; SONICTEAM/PSO
DreamPassport/3.0; SONICTEAM/PSOT
DreamPassport/3.0; SEGA/Profile
DreamPassport/3.0; SEGA/F355
DreamPassport/3.0; SEGA/dreamstudio
DreamPassport/3.0; SEGA/SEGA_TETRIS
DreamPassport/3.0; SEGA/Dabitsuku
DreamPassport/3.0; SEGA/URBAN
DreamPassport/3.0; SEGA/EARCADIA
DreamPassport/3.0; SEGA/EARCADIA/@barai
DreamPassport/3.0; SEGA/NETOUGOLF
DreamPassport/3.0; SEGA/SAKURA2
DreamPassport/3.0; SEGA/SAKURA3
DreamPassport/3.0; SEGA/Napple
DreamPassport/3.0; SEGA/QUIZ_MEGAMI
DreamPassport/3.0; Smilebit/HundredSwords
DreamPassport/3.0; Smilebit/HundredSwords/@barai
DreamPassport/3.0; Smilebit/MOTTOTSUKUROU
DreamPassport/3.0; SOFTMAX/GOLF_SHIYOUYO_AP01
DreamPassport/3.0; TECMO/DEADORALIVE2X
DreamPassport/3.0; TECMO/DEADORALIVE2N
DreamPassport/3.0; Vis/TRICOLORE

DreamPassport3.15
DreamPassport/3.15; CAPCOM/ELDORADO5 
DreamPassport/3.15; CAPCOM/ELDORADO6 
DreamPassport/3.15; CAPCOM/ELDORADO7 
DreamPassport/3.15; CAPCOM/NET_GIMMICK
DreamPassport/3.15; Hitmaker/CrazyTaxi2
DreamPassport/3.15; KID/Memoff2 
DreamPassport/3.15; KID/PrismHeart 
DreamPassport/3.15; KID/Tentama 
DreamPassport/3.15; KID/Yumetsuba 
DreamPassport/3.15; MediaFactory/Culdcept2 
DreamPassport/3.15; SEGA/add-dc2 
DreamPassport/3.15; SEGA/Dabitsuku2
DreamPassport/3.15; SEGA/OnnnaKenshiAsuka
DreamPassport/3.15; SEGA/opendiceDCONSEN2 
DreamPassport/3.15; SEGA/opendiceDCstoPARIS 
DreamPassport/3.15; SEGA/opendiceDCstoTEITO 
DreamPassport/3.15; SEGA/OUTTRIGGER 
DreamPassport/3.15; SEGA/RRK
DreamPassport/3.15; SEGA/SEGAKARA 
DreamPassport/3.15; SEGA/VF.NET 
DreamPassport/3.15; SEGA/YAKYUTSUKUASO 
DreamPassport/3.15; SMILEBIT/sakatoku2
DreamPassport/3.15; SonicKey2
DreamPassport/3.15; SONICTEAM/PSOV2

DreamPassport3.17
DreamPassport/3.17; SEGA/opendiceDCONSEN3

DreamPassportPremier
DreamPassport/3.2

DreamKey
DreamKey/1.0
DreamKey/1.0; BIZARRECREATIONS/MetropolisStreetRacer
DreamKey/1.0; CAPCOM/SFA3
DreamKey/1.0; CAPCOM_USA/ALPHA3
DreamKey/1.0; Hitmaker/CrazyTaxi2
DreamKey/1.0; SEGA/ChuChu
DreamKey/1.0; SEGA/Custom
DreamKey/1.0; SEGA/F355
DreamKey/1.0; SEGA/JETSETRADIO
DreamKey/1.0; SEGA/MarineFishing
DreamKey/1.0; SEGA/SARCADIA
DreamKey/1.0; SEGA/SARCADIAEU
DreamKey/1.0; SEGA/ToyRacer
DreamKey/1.0; SonicKey
DreamKey/1.0; SonicKey2
DreamKey/1.0; SONICTEAM/PSOEU
DreamKey/1.0; SONICTEAM/PSOUS
DreamKey/1.0; SONICTEAM/PSOV2US
DreamKey/1.5
DreamKey/2.0
DreamKey/3.0
DreamKey/3.0; SONICTEAM/PSOV2EU

PlanetWeb
Planetweb/1.125 JS SSL US Gold; Dreamcast US
Planetweb/1.219 JS SSL US; Dreamcast US
Planetweb/2.004 JS SSL US; Dreamcast US
Planetweb/2.100 JS SSL US; Dreamcast US
Planetweb/2.100 JS SSL US; Dreamcast US
Planetweb/2.606 JS SSL VoIP US; Dreamcast US
Planetweb/2.609 JS US; Dreamcast US(UnrealTournament)
Planetweb/2.613 JS SSL VoIP US; Dreamcast US
Planetweb/3.0d JS SSL pJava US; Dreamcast US