So here it is, latest version of Goxplorer has a couple of new features to help explore and discover Bitcoin's blockchain.

On the non-cosmetic side, apart from bugfixes, Goxplorer now launches block de-serialization using go routines, this simply makes a x3 performances increase.

Now on the features side:

-s permits to specify a starting block (relative, starting at 1, 0 means whole file, not block height-based)
-n can be used to only show a number of blocks
-x computes the block hash
-l uses LevelDB Block Index Record to start at a certain block hash, blkXXXXX.dat file is automatically found and loaded
-e uses LevelDB Block Index Record to start at a certain block height, blkXXXXX.dat file is automatically found and loaded
-d uses LevelDB File Information Record to load a block file from a certain date, blkXXXXX.dat file is automatically found and loaded
-tx loads and de-serialize a single transaction

"Real-life" examples are available on the project's GitLab https://gitlab.com/iMil/goxplorer

Bonus track, I couldn't find a working example of Bitcoin's LevelDB usage in golang, so I wrote blockchain/leveldb.go from scratch, it might help some Go developers.

Comments and ideas are very welcome.

Edit: added -e
Edit2: added -d