With the approaching release of D&D 4th edition, a few preview elements of the new game have been released for general consumption. While not all of them map perfectly into 3.5, some elements can reasonably and profitably be included by a DM into plots they run. Listed here are some optional rules that can be used by DMs interested in trying out elements of the new edition before we move to it in June. If you do choose to use these rules, it's best to warn players in advance about them so they aren't unduly surprised.
Skill Challenges are perhaps the most useful new option. Instead of the usual 3.5 mechanism for resolving a complex skill use, in which you simply have to roll higher than a given number on a d20+skill total, Skill Challenges allow for more creative skill use and less one-roll-resolution of complicated situations.
Second Wind is a mechanism to give PCs a little more longevity in a fight, particularly when there isn't a convenient cleric around. If you run solo plots, I'd recommend you use these rules.
Death and Dying is a painful subject, but it can be made a little less painful with these rules. Or at least it can be made more interesting.
Minions are those popcorn mooks that swarm the heroes. Dangerous in large groups, they don't stand a chance against the heroes one-on-one.