I think, in fact, you're:
An emoticon.
I'll win you no prizes, Nobel-worthy I'm not
A lot of authorities look down on emoticons.
But when you're lost for words, I can help quite a lot
Emoticons fill in the blanks and can indicate humor, irony and sympathy.
And sometimes, if you're askin', I'm the best hope you've got
Or sometimes a big-eyed emoticon will get someone to help you out when they are reluctant to do so. From OP: "askin'" is a play on "ascii'ing"
To signal your intentions to far away spots
Often used in chat rooms
So loosen up, think sideways, you know it's okay
Make a symbolic gesture and try me today
These would be typographical emoticons ;)
Leave a mark, add a dash of good taste, and employ me
Marks and dashes are used to make emoticons
But please don't overdo it, so all could enjoy me
Too many emoticons can become annoying and obscure the message.