Mechanical Switches ~credit to bhlaab/claviertekky
Chery MX Blue (very loud; tactile feedback; 50 g actuation):
The #1 recommendation for typing, but really loud and has minor problems detecting quick double-taps (making them not always perfect for games)
Cherry MX Black (loud; no tactile feedback; 60 g actuation):
Quiet(er), has no trouble with double-taps, but a lot of people find that the keys require a little bit too much force to press and you won't feel any tactile feedback (which some consider a major selling point of mechanical keyboards). These are considered "for gaming" but can also make typing uncomfortable.
Cherry MX Brown
A middle ground between Blue and Black with both strengths and weaknesses. You can't double tap as easily as Black, but it's not as much of a problem as with Blue. There's a tactile sensation with typing, but it doesn't pop quite as much as Blue does. Not as loud as blue, but louder than Black.
Cherry MX Red (like black switches with only 45 g actuation)
Similar to Black switches, except much "lighter" and requiring less force. This can either be a good thing or a bad thing depending on how you look at it. Reds are very rare and tend to be more expensive.
Cherry MX Clear
Like browns, but "stiffer" and more tactile, making them skewed slightly more towards Blue than Black. The level of force required is comparable to a typical rubber dome keyboard. Very rare.
Cherry MX Green (medium stiff, tactile, clicky )
These switches are considered a more stiff, heavier version of the Cherry MX Blues. More releases coming forth will be using the MX Greens.
Resources ~credit to fart
OK, now for static resources, the best at the moment is probably the OCN mechanical keyboard wiki:
GEEKHACK: http://www.geekhack.org/ is THE english-language resource for mechanical keyboards (we also have some excellent wikis, but we're having technical difficulties with them at the moment). You are strongly invited to come join us and geek out about keyboards, gaming, and other geeky stuff. We also have many active design and small-scale manufacturing efforts, as well as an excellent and very active classifieds board (COI note: I moderate this board).
DESKTHORITY: http://www.deskthority.com/ is excellent for local commerce and european language conversation if you're across the pond to the east.
OTD.kr, KBDMANIA.com: Korean-only; the world's foremost keyboard experts.
KBTALKING.cn, others: Chinese-only; the world's other foremost keyboard experts.