This is a first post, so they won't let me put more than one hyperlink, hence manual footnotes below.
Assuming you're looking for a Linux or Windows-based LaTeX distro, you might try TeXLive. If you do a full install, it is by no means small, but it can be run directly from a live DVD. For this you have two choices. You can do a 'live installation', [described here] (see fn. 2, below) which sets up a minimal writeable environment on your computer, while all the input files and binaries remain on the DVD, or you can run TexLive portably from USB and DVD, with no install at all [described here.] (see fn.3 below) Both of these schemes work on Linux and Windows. You need to use the text-mode installer for these.
And if you choose to do a regular install (possible from the DVD or from the net), you will also be able to easily choose between 'schemes', meta-packages that control what components to install. [Screenshots here.] (See fn. 4 below).
The current version of TeXlive is 2008, but the 2009 version should be out fairly soon (within 2 1/2 months anyway). TexLive has an annual release cycle, and they nearly always(!) manage to to get it out in the calendar year of their version number.
Hope that helps.