i've been doing the same thing..well, applying online, and via regular mail. i haven't gotten a call back yet, except from one place...and i didn't end up liking them (they couldn't even send me a confirmation email with MY name in it, I got someone else's)...
call them and ask...unless on the page you applied at it says, "do not call." and even then, you could always call if you wanted to anyway. i've been thinking about calling some of the places that i've applied to that say don't call....fuck that, call me back then!