The tardis big bang is due to end in June or July, and seriously, there better be some good fic out of that - they've had enough time (since Oct '07). SGA BB only has 5-6 months, I think, and their word count is twice that of TBB.
All BBs have a different focus, so I'm not sure what the Heroes one would be. The HP one I think is all Harry/Draco, the SPN one is all Sam/Dean or RPS. Last year SGA BB was limited to 3 specific parings (a het, a femslash and a slash), but they all ended up being slash (Sheppard/McKay in this case). This year is different, as all other parts of SGA fandom protested and so the doors were thrown wide open for any and all pairing/non-pairing.
Re: Big Bang stuff
All BBs have a different focus, so I'm not sure what the Heroes one would be. The HP one I think is all Harry/Draco, the SPN one is all Sam/Dean or RPS. Last year SGA BB was limited to 3 specific parings (a het, a femslash and a slash), but they all ended up being slash (Sheppard/McKay in this case). This year is different, as all other parts of SGA fandom protested and so the doors were thrown wide open for any and all pairing/non-pairing.