There are devices with more RAM (32MB or 64MB) and with USB port(s) where you can mount a flash drive / external disk and install anything (like Transmission, or even Samba) on it and use as a poor man's NAS. For example the TP-Link MR-3020 is pretty much hackable [0].

[0] - http://wiki.openwrt.org/toh/tp-link/tl-mr3020