I would like to use an old t-mount lens on my Nikon DSLR, is it possible?

I have a Nikon D3000 which uses the F mount bayonet lenses.
My father-in-law has many old lenses with a 42mm t-mount and I would love to use some of them with my Nikon.
I've heard of mount adaptor and have done some searching on Google but I have drawn blanks.
Does anyone know if it's possible to get an adaptor for this particular need? If so, where do I get them from?

Ask in a camera shop or attempt to screw the lens onto the main lens. If it fits, it'll work.

Adorama carries an adapter
http://www.adorama.com/...NTMNK.html
You will have to use manual exposure with no autofocus or metering.

This should be just what you need:

http://www.rugift.com/photocameras/m42-nikon-af-optical-adapter-programmable.htm

Of course there will be no auto focus so you'll have to learn to manually focus.

The T-mount can be adapted to fit on a Nikon camera and focus to infinity, there are quite a number of sources for adapters, which vary in quality, ebay are the cheapest but quality can be dubious, SRB griturn are machining specialists who will produce high precision parts http://www.srb-griturn.com/t2-mounts-245-p.asp and there are a whole range of products in between.

One word of warning you won't get metering (let alone auto exposure) with these lenses, you'll need to expose by histogram. Non CPU lenses should really only be used with the D200/300/300S/700/D1 series/D2 series/D3 series which have metering support for non CPU lenses.