That depends on your ability to be scintillating in text. I've had fantastic conversations through email, chat, and even with a penpal who wrote to me on high-quality stationary (he pulled it off, I swear), and I've had email exchanges that made me want to break my computer just for an excuse to get out of them. A few warnings: 1) don't try for an "in-depth" conversation right away. Be funny and interesting and let the conversation flow naturally. Ask her about things, tell her about things, don't try to dive immediately into her soul. Guys (well, people of any ilk at all, really) who try to force profundity are unbearable. Banter is your friend. 2) Don't let it go on to long. This is true of any social interaction ever, but when you find a high note to end it on, do so. 3) Don't entirely suck at grammar. Eloquence is so, so attractive. 4) Read the signs. That's harder online, but if her answers are always much shorter than yours, then she's either terse or bored (hint: there are very few terse girls).
Or, if you've got sexy handwriting, you could choose a signature stationary send her a pithy letter. It works sometimes.