Well, that was something. It appears that this party is still severely lacking in teamwork and coordination.
Luckily, this was an easy one. Had you faced a tougher or more numerous foe...I'd hate to think how things might have turned out.
So, let me give you guys some tips for future battles.
Changing Actions
As long as I have not yet resolved the round, it's possible to change your actions. (You will need to roll initiative again for the second action, however.)
For instance, let's say Arkos the Fighter, Daos the Mage and Marik the Thief are wandering through the wilderness when they run afoul of a dozen angry orcs.
Arkos' player posts first:
Arkos wrote:Drawing his sword, he holds it aloft. "We are already dead," he announces to his companions. "We go into battle to reclaim our lives! Chaaaarge!" He then runs toward the orcs, attacking the first one he reaches.
Daos' player posts second.
Daos wrote:"No, wait! They are all clustered together. I can take them all out with one fireball!"
As the DM has yet to resolve the round (he's waiting on Marik's player still), if Arkos logs back on and sees the new post, he can then post a second time.
Arkos wrote:Hearing Daos' warning, Arkos skids to a halt. "Very well, cast your spell. I'll defend you." Arkos will remain where he is, attacking any orcs that get too close.
This is all perfectly acceptable, so long as the round hasn't been resolved yet. If I resolve the round, then it's too late to change anything, obviously.
Holding Initiative
Sometimes it can be difficult to coordinate actions, due to initiative. What if instead, Arkos decides he'll charge the surviving orcs, but only after the fireball is cast? But if Arkos beats Daos in initiative, he'll run into the fireball's range anyway. To avoid this, Arkos can specify he is holding his initiative until AFTER Daos casts the fireball spell.
If this is specified, should Arkos beat Daos in initiative, he will wait and won't move or act until immediately after Daos' turn is over.
If/Then Actions
It's possible to list a few options, depending on what your teammates do, to help avoid slow down in posting. For instance, suppose it's fairly standard procedure for Daos to toss a fireball when the enemy is all clustered together, and Arkos knows this. Arkos may have specified, then, in his first post that he would stay where he was and defend Daos if Daos casts fireball. If Daos does not cast fireball, Arkos will charge the nearest orc. If Daos casts fireball, and no orcs reach Arkos before, then Arkos can specify he'll charge any survivors after the fireball (holding his initiative until after the fireball).
Utilizing these three techniques can help a lot in coordination and teamwork during combat. Of course, none of them will solve the problem of the PCs all shouting orders to each other, and ignoring them. That's something they'll have to work out themselves.