Eh... why don't you use bigbangindex (here is the masterlist with all bigbangs (http://bigbangindex.livejournal.com/profile)). So is also bigbangmaster where you can find masterlist of various bigbangs.

You probably have some of these, but i'm just c/p'ing my lists

SPN/SPNRPF specific bangs

1upona_sabriel between rounds
balthazar_mini story/art due May 12, posting May 14
crowley_bigbang Posting begins on June 18th
cwbigbang summer round sign-ups coming soon
dc_dystopia reverse bang round, sign-ups open
dc_everafter posting
deancasbigbang sign-ups open
deansbaby_mbang Posting starts April 29
debriel_mini sign-ups open
gabriel_bigbang posting
j2_afterclass new round sign-ups soon
j2_everafter between rounds, next one November
j2_fairytales between rounds
j2_kane_bigbang sign-ups in May
jimmybigbang between rounds
john_w_bigbang between rounds
pre_post_spnbb Posting starts June 20
sabriel_mini between rounds
samdean_otp between rounds (mini-bang has it's own tag)
sassy_minibang between rounds
sncross_bigbang posting starts June 1
spn_adambang Posting August 1
spn_gen_bigbang between rounds
spn_illuminated claiming open now
spn_in_space between rounds
spn_j2_bigbang Posting starts June 6
spn_j2_xmas between rounds
spn_kinky_bang sign-ups open
spn_meanttobe between rounds
spn_reversebang between rounds
spn_slackers_bb cancelled due to everyone slacking
spnapocabigbang sign-ups open July 15
spnaubigbang sign-ups open May 1
spnfemmeslashbb between rounds
spnslashbigbang between rounds
super_disney posting May
superwho_bb posting starts April 15
swl_bang posting starts August 21

Multi-fandom bigbangs you can write SPN or SPNRPF fic in

100k_supernova posting now
30kin3 posting starts June 5
angelic_bigbang between rounds
angstbigbang posting now
apocabigbang sign-ups open soon
au_bigbang posting starts August 8
bdsm_fandom Posting starts September 10 (bigbang has own tag)
big_bigbang between rounds
bigbang_mixup art claims open
bigbangbuffet posting now
casestory posting starts June 10
crackship_bb sign-ups open
christmasbang between rounds
crossbigbang posting starts June 11
dark_fest posting now
dystopiabigbang sign-ups open
femmeslash_bang comm seems dead
fivetimesbb posting now
hc_bigbang posting starts May 1
heroinebigbang posting starts June 30
het_bigbang sign-ups start May
history_bigbang posting now
journeystory between rounds
kink_bigbang between rounds
lovebites_bigb no rough drafts turned in
mentorshipbang comm seems dead
mpregbb between rounds
pictures2words comm seems dead
piratebb between rounds
polybigbang posting now
queer_bigbang posting starts August 15
recast_bigbang abandoned by mod mid-round
rpf_big_bang sign-ups open May 15
scifibigbang posting starts August 20
serialkillerbb sign-ups open
spacebigbang author sign-ups closed, artist sign-ups June
syfybigbang comm seems dead
thelittlebang between rounds
thief_bigbang comm dead
timetraveler_bb posting starts May 22
undeadbigbang between rounds
vampirebigbang sign-ups open April 23
werewolfbigbang posting starts June 1
witchesbigbang posting now
zombi_fic_ation prompting now, sign-ups/claims start April 23
zombiebang between rounds