Fix is a new showcase for shoestring film and video work in Birmingham. They've held a half-dozen or so events so far, and continue to host regular events. If you've made a short animation or experimental showreel, they'd be happy to have details and a CD-R or tape. The Light House also hold regular quarterly meetings of their Animator's Forum network, and have recently launched a similar Screenwriter's Forum. Digital video is still one of the more expensive forms of new-media, but even here the costs are dropping.
Exposure is a UK network for young film makers.
And of course, you can now distribute your trailers on the web at low cost too.