You have gotten a lot of good tips....timers, songs, etc....
here's a few more: try singing a few songs. Happy Birthday, Twinkle, Twinkle and play her favorite song on the radio or iPod....
have her time the songs and write down the times. Do it again.....help her grasp the "true concept of time" by comparing to something she knows.
Or---this is what one of my boys loved! Get a stopwatch (they're $7 at WalMart if you don't have one). It might be the best $7 ever spent.
Some kids cannot grasp the concept of time passing unless they see it. Let he play with the stop watch and learn how to use it. Then, give her reasonable time lengths for getting dressed, taking a shower, etc....and she starts and stops the watch herself. You need to give her ownership of this. When she accomplishes 3 tasks in the time limit and shows you the stopwatch to prove it, she gets a special something....
extra half hour TV,....extra time outside to play....
If these fail, and I got out on a limb here.....she likes having things done for her and knows you will bail her out if she gets in trouble. Not saying this is you, in any way, but I know of a neighbor who bails out her youngest (of 3 girls) daughter from all distress. She tells me her youngest daughter has a lot of her mind and is more sensitive than the other 2. She (daughter) continually forgets gym clothes, homework, the permission slip, lunch etc...b/c she can call Mom and Mom will drop what she is doing and take it to her.
I was telling her one day THIS was nuts---her daughter was almost 15 & still doing this.
So with great "Mommy guilt" one day daughter called and needed her tennis shoes brought to swim practice for dry land training. Mom told her "no." Daughter took wrath of unhappy Coach and then amazingly started remembering her things.
So, bottom line, if all else fails, your daughter might be partially dressed and have to go to school in her top, pants and slippers.....because she didn't focus on time. Or she might have to go to volleyball and tell the coach she doesn't have her knee pads b/c she ran out of time looking for them.
It hurts to do this....but it helps them grow.
Best of Luck.