I'll answer my own question, since I'm now at the DEL airport.
JAL uses the Plaza Premium Lounge, which is halfway decent and open to OneWorld Emeralds. JAL and I think one Cathay flight are the only two airlines using this lounge which have evening departures, so it's not too busy. I think most of the European and North American flights leave late at night.
The Kingfisher lounge mentioned in on the OneWorld website no longer exists.