Thanks for all the tips so far, this is quite helpful.

I think I am going to look into the finishing-nail based hooks.
Cleanup-wise, they seem a safer bet than the big plastic-anchored
stuff and I don't need that much holding power.

When I was talking about adhesives I was talking about posters only -
i.e. using two sided scotch tape or so to hang posters and papers up
on a wall. Not about adhesive-based hooks to hang up stuff up with.
I am pretty sure any glue strong enough to hold up 6 lbs will also rip
out the wall's paint when it leaves, regardless of claims by the
manufacturer.

Btw, is it just me or is there a real lack of furnishing books for
renters? Many of us will live in rented accommodations for years and
may want to tweak them a bit.

Yet, all the books I've seen assume:

a) you have tons of space to play with.
b) you own the place so you can rip it apart.
c) you have tons of money so that, in addition to a. and b. you can
afford super-duper custom furniture if you do want to save on space.

I had Sarah Susanka's Not So Big House book and its floor plans looked
more like Not So Small House to me. Still, she at least tries to be
realistic.