Unicorn "Miner" CodeGolf
Javascript, 104 (114 chars - 10 bonus)
All due credit here.  Simply posting this to get the &quot;first answer&quot; -10 bonus ;-).
p='$.post(&quot;/unicoin/'
setInterval(p+'rock&quot;,function(o){'+p+'mine?rock=&quot;+o.rock,StackExchange.options.user)})',2e4)

setInterval accepts both functions and strings of code. After susbtituting the variable p, the following gets executed every 20 seconds:
$.post(&quot;/unicoin/rock&quot;, function(o) {
    $.post(&quot;/unicoin/mine?rock=&quot; + o.rock, StackExchange.options.user)
} 


Edits are welcome.  I don't know javascript well enough to really competitively golf this.