Just to add a few more to Cpt's excellent list:
Chaos - Chaos Sanctuary experience farm (if they allow leechers its the best way to level up fast)
Baal - Baal run, also great experience for high levels.
Ubers - Either completing uber Tristram for the torch or farming uber Meph's skeletons for xp (no longer possible to farm uber meph for xp as of patch 1.13)
Crush - classic rush (Rush on classic then promote to expansion, allowing you to bypass the need for killing baal)
Rush - normal rush through all 5 acts. Typically people who are doing rushes will look for 'staff chars' which means those that have a completed horadric staff ready to go for duriel in act 2. This saves the time of having to gather the components of making the staff.
There are also some abbreviations for commonly used items/runewords:
hoto - heart of the oak
hoz - Herald of Zakarum
tals - typically refers to tal rasha's rainment set for the sorceress (tals ammy, tals armor, etc)
Anni (typically followed by its stats) - Annihilius, the unique small charm dropped by Diablo clone on certain servers where a # of SOJs have been sold. i.e. 20/20/10 anni is considered 'perfect' with 20 stats, 20 resist all, and 10% more experience. Sometimes people just post the first 2 numbers.
Torch - Hellfire Torch. Typically followed by stats as well. 20/15 sorceress, for example. Means 20 to all stats 15 to all resists sorceress torch. sometimes they're abbreviated by the class: storch, ptorch, etc.