Drawing a cube in ASCII art

Python - 248 243 230 227 191

Slightly messy but it basically prints the cube line by line(using a string buffer).

t=v=h=input()/2
s,p,b,f,n=" +|/\n"
l=p+"-"*t*4+p;S=s*4*t;k=s*h;K=b+S+b
r=s*t+s+l+n
while t:r+=s*t+f+S+f+s*(h-t)+b+n;t-=1
r+=l+k+b+n+(K+k+b+n)*(v-1)+K+k+p+n
while v:v-=1;r+=K+s*v+f+n
print r+l

Thanks to @marcog, for pointing out the first line, @ThomasO for pointing out the second line and to @Juan for making me realise I can combine lines.

Python - 179

h=input()*2
j=d=h/4
q,e,u,p,k="| \n+/"
w=e*d
s=p+'-'*h+p
i=''
o=e+w+s+u
v=q+e*h+q
while j:o+=e*j+k+e*h+k+e*(d-j)+q+u;j-=1;i+=v+e*j+k+u
print o+s+w+q+u+(v+w+q+u)*(d-1)+v+w+p+u+i+s

I'd like to note that I took some ideas from JPvdMerwe (Using a string to print once, and the one-liner for that I didn't know was correct syntax in Python).

Golfscript - 96 chars

~:<2/:$){' '*}:s~'++'<'--'**:^n$,{.$\-s'//'2s<*:&*@s'|':|n}%^$[$s|n|&|]*$s'+'n$,{n'/'@s|&|}%-1%^

Most of the compactness comes from aggressively storing almost everything to a variable (unless you include being written in golfscript).

<    n
$    n/2
s    {' '*}     # top of the stack becomes a string of that many spaces
^    '+------+'
&    '      '   # 2n spaces, i.e. 2s<* or <s2*
|    '|'

A couple of other small tricks here.

1. 'LR''str'* -> 'LstrR'.
2. Since we need to reverse the order of lines in the last array, we opt to do this after generating the text instead of before. This allows us to save one character because the spaces before the '/' only needs to go past two stack elements (@) instead of 3 (@ .. \).