I first came to Mudcat in, I think 1999, as a guest, on the recommendation of a friend as a good resource for song lyrics. This proved true several times more before I joined in 2000. Have checked what my first post was, and it was a Lyric Req for "Sam the Skull" (I'm a Glasgow Cat)- typical of my love of comic songs. I have apparently contributed to nearly 2,500 threads since!
I have made friends through Mudcat, some I have met,some merely conversed with via the forum, been to "Mudgathers" etc.
I have found that some people I already knew were fellow-Catters - all hiding behind our pseudonyms.
I have learned a lot from other Catters all over the world, and am very appreciative of the knowledge base of some of our members, and the trouble they take to impart information.
I have tried to help others, e.g. people who have asked where to go for music while visiting Edinburgh, sometimes met them myself, or pointed them to friends who could help.
I have had many a laugh at some of the really hilarious posts. And I've had lots more song lyrics, this site usually being my first port of call if looking for something.
This is all the good stuff about Mudcat: as some others have said the real downside is the nastiness that goes on in some quarters, point-scoring, the "great I am" mentality that pervades with some: no you don't have to read it all, but thread titles don't always predict what outpourings of venom and personal insult are going to follow!
I have tried not to be too rude to anyone (beyond pointing out that they have not read the thread properly and just duplicated what's already been said!)I have only once had an abusive remark directed at me, from one of the forum's regular spatter-gunners, so I took it with a pinch of salt and didn't reply - not stoking your flames, mate! My own maxim is "never say on a forum what you would not say to someone's face" - whether under cover of a pseudonym or not. And I don't mind people knowing who I am: nothing to hide, your honour!
I did for quite a while contribute more to the Scottish Footstompin Forum, but this has evolved into being not much more than somewhere to advertise your up and coming events: most of the discussion has disappeared, it never had anything to match the DT: there were occasional lyric requests, usually answered, but no database of them.

Then of course, there's Facebook and Twitter. I got barred from one Facebook page for pointing out, politely, that they had wrongly attributed the authorship of a particular song: I was told n to "stop stirring it" - when I protested meekly that, surely, the giving of correct information was not stirring, I was dumped and blocked! Just imagine if that admin became a mudelf! There would be a whole army of you off here!