I will vote only for a few where I actually know something of.

2008's best JCS'er: n/a
2008's best CTF level: Undulation
2008's best Battle level: Enter the Chaos
2008's best (non CTF/Battle) level: n/a (Lazy)
2008's best MP Pack: Err.. More CTF Levels? (I really enjoy some of the levels in there )
2008's best SP Pack: Episode Four: The Resistence
2008's best tileset/tileset conversion: All 5 are pretty good, not voting ;( And also I feel like I might be biased here.
2008's best music: n/a
2008's most improved JCS'er: n/a