Well, it's not called the summer drought for nothing.
What few games that do get scheduled for the summer months usually get pushed back because there's no real driving force setting the deadline. (unlike the end of the year holiday rush).
I might suggest some games that are out now and would provide you with a solid challenge
Burnout Revenge - Really fun and quite a challenging single player experience, plus the online community is still fairly large
Guitar Hero II - easily the most popular game right now, hard and expert modes are places for "legends" to prove their worth
Ninty Nine Nights - Quite challenging and a good mix of beat-em-up and RPG elements (don't judge the game by it's demo)
Rainbow Six Vegas - it's like Gears of War done right, very challenging (but not impossible) to complete and again has a thriving online community.
Ridge Racer 6 - if you're looking for some "pride" achievements this is the game... the bar is set ridiculously high. if you can complete the offline achievements you're a racing God... though they've been cheapened a bit by game savers before last Fall's update
Splinter Cell Double Agent - awesome game... and a good mix of challenging online/offline achievements.
Tony Hawks Project 8 - completing all of the games goals on the sick difficulty is quite possibly one of the hardest achievements in any game on the 360.
For some fun games and some easy points
Enchanted Arms
Phantasy Star Universe
Tomb Raider Legend
eM and PSU are easy but time consuming... Tomb raider is fun and will take you about 10-15 hours.
... on second though... yeah go do FFXI... it will give me a chance to catch up to your gamerscore
