The first is friends-group support. Once the group code is restored I'll work on making it possible to check only for new entries in a particular set of your friends. This is useful for people with large friend groups and who typically use a filter. This is actually supported by the LJ protocol.
The second feature (on which I really want comments) is to add thresholding to the "NEW" indicator, that is, to notify the user only when a certain (small) amount of new entries is reached. This may also be useful for people with lots of friends, for whom notification of one new message will send them to their friends page all the freaking time. It can work by actually violating the protocol and checking for new entries even after the first one is noted; the client takes responsibility for stopping its checks (and notifying the user) only after the threshold is reached. Easy to implement, though there are a few implementation issues to decide. Of course, there'd be a pretty low hard limit on this threshold (say, 5? 7?), and it'll default to off (==1) entirely.
Would you use feature #2? Is it just bloat, or too evil?