Mecanum wheels are awsome! It is surprising that they are not more popular and that it is difficult to find them (and they are very expensive when you can find them!)... Anyway, thought I would contribute this robot featuring macanum wheels:
[youtube=425,350]CGZBtZbZ714[/youtube]
edit by admin: I fixed your youtube link, remember to just put the jumbled letters between the brackets and not the entire http link