re LTC:
Not too long ago it went up a full 50% in less than a day, so waiting through the dead time is worth it.
I try to go against the crowd, and also avoid being on the wrong side of a huge move.
Primecoin (xpm) is something only a "complete fool" would be interested in right now, but it is probably set up for a 50%+ short-term up move.
Also, some of the older "failures" (i.e. PPC, Namecoin, Earthcoin, Devcoin, BBQcoin, etc) are good to buy low, since they have a following and are "almost certain" to eventually have a good % rally.... BUT you need to start slow and have BTC in place if/when prices go even lower.