Remember that all these projections are based on assumptions that aren't generally true in the midterms:
1) That Dems will outvote Reps, and they will vote Democrat
2) That Indies will vote at twice the rate they generally do, and will break Democrat
3) That women will outvote men
4) That the 18-34 age group will vote at twice or three times the rate they normally do, and vote Democrat
5) The 65+ group, which usually has the highest turnout, will vote at half the rate they normally do
6) Republicans won't turn out at the rate they normally do
If all those hold, it will be a great day for Dems. Problem is there isn't alot of historical precedent that it will, not even '06, beyond the fact that the GOP didn't turn out well that year.