If you have time, Rune Wiki has all the things you would want to know or want to know in time line format. I'll try to give a condensed version.
Six months would be about November or December. So...
1. Thanksgiving Event
2. Some updates, minor and various
3. Christmas Event
4. Some new quests added
5. Improvements to Barbarian Assault Minigame (including option to recolor abyssal whips)
6. Commercial Competition and Orb of Oculous
7. Chance to get double runes in Runecrafting for bloods, deaths, and laws
8. More quests and content added to slayer especially
9. New Runescape Lobby Login Page
10. Bonus XP Weekend
11. Easter Event
12. DUNGEONEERING Miniga...I mean skill.

Anyways, I think that's really all you need to know. Like I said, if you want to know more, go to those time line pages. Otherwise, all I'd say you missed is a couple holiday events, new quests, content updates, and a new skill (that's not really that good imo). Hope that helps.
2010 Time Line of Runescape2009 Time Line of Runescape