.. i'm assuming you're looking for older stuff?
Check out the rest of the crew Big L was down with, DITC (diggin' in the crates). They released a bunch of albums throughout the 90's , most of them better than Big L's. There are definitely a few under-appreciated gems in their catalogue, namely O.C.'s Word...Life, Diamond D's Stunts, Blunts and Hip Hop, Showbiz & AG's first couple and Lord Finesse's debut. Trust me, if you liked Big L's first, you will love these.
As far as non-DITC-related east coast hip hop, check out another heavy weight NY crew called the Boot Camp Clik. They released at aleast 3 great albums in the 90's.. Black Moon's Enta da Stage is one of the greatest albums of all time, and no doubt influenced guys like Mobb Deep + affiliates, Cormega, etc. The next two you may've heard of - Smif'N'Wessun's Dah Shinin' and Heltah Skeltah's Nocturnal.. both great albums. Another album that came out around the same time that is also a favorite of mine is OGC's Da Storm.
There's so much more.. i could really go on for hours, but if you check out all of those albums, you will've heard a big chunk of the best the east coast has to offer.