Rushing has become increasingly popular (at least it seems to me) since entrenchment came out. It is a race to keep the player down before starbases come up and the lines are drawn.
One of the hardest to counter is the vasari starbase rush, properly executed it will leave you with little choice but to waste your early game fleet in futlie attacks against it.
The TEC Sova rush works on smaller maps, but it has been awhile since i have seen this used for more than an annoyance.
Personally, i like a mothership and illum attack as early as i can get illums out.
There are others, increasingly obscure, like the Antorak rush.
So what is your favorite rushing tactic and why?