Wow! I've heard of chaku-melo (着メロ) but haven't known about hatsu-melo (発メロ) or that there are websites dedicated to the subject.
Here's one.
Being a JR Chuo Line person myself (travelled on it every day for 18 years of my life!) I didn't know about different tunes that Yamanote Line stations boast. My own local Chuo Line station has 4 different tunes, though I swear I've only heard 3 of them. The 4th must be reserved for special occasions.
You can also listen to canned announcements on trains (車内アナウンス) - 4th link from the top. Very soothing