Two ways for it to happen you can spend them and pay the fee, they will arrive as a single unit. Alternately you can send small batches to another address you control (say at mybitcoin, mtgox or bitcoin running on another computer you own) and then send in larger chunks from there till you can send them all at once with no fee. You have to wait some time between stages of this process for the transactions to mature to the point where they won't need a fee just because of age.
Thanks to all of you for the explanations. I think I understand: Large fees only occur at the point where lots of small payments are combined, subsequent transactions are not affected.
Sorry if I´ve wasted your time, but thanks for your patience.