The Dana Dolly is a super-slick small portable dolly system. It provides a stable platform so the camera can ride on speedrail of any length, creating a quick and easy means to achieve smooth horizontal camera movement without a full-size dolly or dolly grip.
I own the following:
Dana Dolly system with Universal track ends
Custom T low track supports
Matthews slider stands (extra low-boy jr.)
Double-riser junior stands
As an alternative to the Dana Dolly, I also own a set of Glide Gear skate wheels which can be mounted directly to the tripod spreader, creating a miniature dolly which can ride on track placed on the floor. This method works well when moving quickly indoors (height adjustments happen via tripod, rather than stands) or to keep track further out of frame when pushing in or out.