I use the line from the bow eye to pull the boat partway on the trailer. With my particular trailer, what works best is when the rear most roller is at water level. It has a notch that will capture the bow. Once it the first foot or so is across, I can use it to lever the boat for a straight pull up the remaining rollers. My bunks are configured a bit higher than the rear roller, so in the last stages of pulling out the boat, they will take over and only the part of the hull with a pronounced V section sits on rollers. This took several seasons and trailer configurations to work out; I now have the boat perfectly positioned on the trailer every time, without having to drive the car into the water or have someone splash around the boat.
The trailer came with a kind of gangplank, so I can walk back on it to attach the winch line. I leave the bow line attached and once the boat is pulled up to the winch post, I take a few turns with the rope around the winch post and lead it back to the foredeck cleat. Having lost a bow eye off the boat once during retrieval, I prefer the redundancy this gives me. Same as I use two tie-downs where I see many other dinghy sailors use only one.
Finally, the last bit of bow line is used to take a few wraps around the mast for trailering. The mast is also tied down to the cuddy cleats and secured with two separate bungees in the back (on a mast support held in the gudgeons).
I've had not only the bow eye fail on me, but also tie-down ratchets and I've managed to get distracted and/or made some mistakes in securing mast or boat. In all of these cases, the redundancies have paid off.
The final bit of re-purposing for the bow line that I have come up with is to tie a loop into it and give it to a crew member or passenger who wants to sit out as something to hold onto (as I normally belay it on the cuddy top when under way, that works really well).
I think that must easily be the piece of line with the most uses on my boat.