There are a couple of cleaver things you can do with an old pringles tin
http://www.turnpoint.net/wireless/has.html
But using mainstream kit - without spending silly money the answer is no.
(almost) All boosters I've heard of work at the transmitter (A)end .... if the signal won't reach .... you basically add extra transmitters (waps) untill it does
the only sure boost you could give the system would fit at the A end.
Either buy an extra wap, convert the existing wap to one of the newer higher coverage devices or fit a High Gain Antenna Kit for TNC Connectors (�28-30).
and get the landlord to put it in his window ... or attic ... or .....
An external wireless adapter for your laptop MIGHT help - you would certainly have more control over it's position.
... but then again it might not.
wireless (802.11) can be tricky even in an ideal situation .... when you are "borrowing" a connection ... you just have to learn to type standing on one leg with your head in a cupboard.