+1 for arctic silver. There are 2 types. Regular conductive silver and ceramic one which is not conductive. For diodes use none conductive pads.
I hired an Italian guy to do my wires. Now they look like spaghetti!
Arctic Silver 5 (the paste) used to be conductive, but apparantly they have changed the formula. The website now says it is non-conductive, but I would be careful nonetheless.
Arctic Silver Thermal Adhesive is non-conductive, but quite capacitive. The strength of this epoxy can be changed by 'cutting' it with AS5.
Arctic Alumina thermal paste is non-conductive and non-capacitive either. It is not as effective as Arctic Silver, but is the preferred alternative for situations where Arctic Silver is unsuitable.
Arctic Ceramique thermal paste is also non-conductive and non-capacitive. It is cheaper than Arctic Silver, while slightly less effective, can be used in place of Arctic Silver where electrical insulation is needed.
I use Arctic Ceramique for all my laser stuff. The silver is better but will have an unnoticeable advantage. Thermal transfer is only as good at your sandwiched heat conducting substrates. If your extra paranoid, use something with liquefied diamond.
Oh, don't forget indium foil. Great conductor without all the mess.
IC Diamond rocks. Two downsides though: I find it really hard to work with. It doesn't "flow" as easily as other thermal pastes. Their site, http://www.innovationcooling.com/index.htm, basically states "make a bead and smash flat" - They aren't kidding. The other is price.
Ceramique is pretty good, easy to work with and cheap.
I should have a gram or so of the IC Diamond stuff left. If I find that tiny container I'll ship it up to Mech to play with.