1st. You can buy bitcoins at
Coinbase (for USA) or
Bitstamp (for Europe)
2nd. Things you can do with bitcoin, you can buy domains at
Namecheap, some hosts accept bitcoin, Overstock, porn sites like camdough and verotel accept them,
ScoreLand accepts them, tons of shops, stores, websites, etc accept them see list of
shopping with bitcoins here. (tons!)
But, thing that makes them great (imo) is when you are doing peer to peer purchases, no middle man needs to be there, like paypal, paxum, banks, and what each of them entail are fees, FEES, rules, monthly fee, yearly fee, questions, waiting, more fees etc.
I can totally understand that some ppl wont find them useful, so maybe they are not for everyone...... but the feeling I had when I bought that network peer to peer, man, i am totally behind this bitcoin craze. Banks dont get 1 cent of my $