Spoiler
Eh, these could be separated. I wanted to post them together, for some reason. They're kind of companion pieces.
Inspiration strikes!
I can't talk, I can't listen, I must write, write, WRITE!
I must capture this elusive thought before it slips away into nothingness, fading away to the faintest whisper of a dream, so close I can touch it; yet so intangible I cannot grasp it.
Do not interrupt me until I am done!
If I don't seize this now, I may never get it back!
I don't know when I'll be finished! Do you know so little of the ways of a writer?
I don't know how long this will take! I don't know where this thought is leading me!
I--
DANGIT.
My inspiration is gone.
Spoiler
And now, I personify Writer's Block! Yay!
Hello, Writer's Block. I am not pleased to see you.
No really, go away! I need to get some work done.
Why won't you leave? Look, I have a paper due in three hours. I have to write something.
Please? I'm begging. Will you accept bribes? Because I have chocolate.
Okay, maybe I can ditch you by going for a walk. So long, writer's block! You'd better not be here when I come back!
......
Writer's Block. Go AWAY.
...please? It's already been an hour.
Seriously. Haven't you had your fun? This isn't nice. You're horrible. Really.
...maybe surfing the web will help.
What?! One hour left?! WRITER'S BLOCK!!! I AM GOING TO KILL YOU!
FINALLY. It's done. HA! I conquered you, writer's block! YOU HAVE NO VICTORY!!!
...now, what do I write next?
WRITER'S BLOCK. I HATE YOU.

You described that 'elusive thought' so well. I think a lot of writers can relate to this. The wording is great too.