Not sure what more I can add?! We average around 10 to 15 people nightly in Ventrilo now, often 2 dozen on Saturdays - that is many people voice chatting while interacting with those in text chat. If you haven't used it, nothing we can say will express the joy of making new friends, sharing personalities, busting each others chops (heck, we even moved the Mason/Dixon line up into Central Pennsylvania through the interaction of members getting to know each other) but you need to know that whether you are in voice or text, you are hearing and reading each other, making it a multi-senses experience.
Sure, text chat has a mystique about it, and I can imagine people staying in that format if that is where they are comfortable - but to have the voice option (which to the most part is very clear and quite active) really makes for fun listening even if you choose to always text.
There is lots of room for more people and Ventrilo can expand to many times more members then currently use it, so the ease of installation, quick setup and small resource usage makes it a great communication aid.
As JP said, you make friends, not just meet other members. And having your questions answered in the forums is great, but it reminds me of playing chess through the mail compared to the instant speed of voice/text chat. We've used it about 2 years now and all the original gang, plus a boom of new members has really added to the fun, where else can you talk with multiple Continents at once while surfing the Net or playing online games or whatever you are into?
Enough about Ventrilo, we still have a plain TEXT CHAT JAVA APPLET, no one really uses it since Ventrilo handles both voice and text so well - but if you choose to go to an empty room, just so you don't have to install a megabyte program on your computer, then I'll dig up the link (unless someone has it handy - I'm at work now) and post it here. Be warned though, it is a lonely place, meanwhile a dozen or members might be just a click away. This reminds me of a really wealthy guy I worked with who always kidded that he still had a black and white TV, because he was waiting for them to perfect color. Who knew back then that HD was coming, now he finally has a color TV, a really nice one. I like to think of Ventrilo Chat as color TV, it is a major step up from plain text chat, whether someone believes that or not. Again, you need to see for yourself, that's the only way to know.
As Buzzbee said, you can tell who is on Ventrilo from the forum MAIN PAGE at the very bottom in a white window, you'll see the list of who is currently online in chat - you need to refresh the page occasionally to see who came in or logged of because the little white box doesn't auto refresh. But if you already have Ventrilo installed, you click on the IP link in that window and it launches you right into our Ventrilo main Lobby where we all me and chat - then occasionally members spin off into the many other chatrooms for private conversations or when talking different topics or online gaming.