Re: There is no finish line...
Good idea to make this thread! There are tons of significant records that Federer could relatively easily beat by simply playing at a solid level for another few years, building upon his past achiements. Which is nice for us fans, even if he performs below his peak standard there will still be new records to enjoy.
Some additions that I didn't see yet in the previous posts (sorry if I missed one):
Consecutive Slam 4th rounds (25 now, Lendl has 28)
Consecutive seasons with 20+ Slam match wins (6 now, Lendl has 7) [needs USO 2010 SF]
1 Olympic Gold Medal (0 now, 13 players have 1) + Career Golden Slam (Agassi has this)
Most Slam semifinals (25 now, Connors has 31, Lendl 28, Agassi 26)
Most consecutive quarterfinals at Australian Open (7 now, Edberg has 10, Lendl 7)
Most runner-ups at French Open (3 now, alltime [since 1925] record is 3 shared by 8 players) [a bit questionable if this should be included]
Most consecutive quarterfinals at French Open (6 now, Connors has 7, Vilas, Lendl 6)
Most consecutive quarterfinals at Wimbledon (8 now, Connors has 11, Sampras 9, Becker 8)
Most consecutive finals at US Open (6 now, Lendl has 8)
Most consecutive seasons reaching a Slam final (8 now, Lendl, Sampras have 11, Borg 8)
Most match wins at YEC (29 now, Lendl has 39, Becker 36, Sampras 35)
Most match wins at Masters 1000 events (209 now, tying Agassi for the record) He should take this record this summer.
Total weeks in the top 2 (don't know precise current number, Sampras has 376 weeks)