Lead with the benefits

In between writing up course notes for a class I am teaching tomorrow I have been trying to think of catchy lines for banner ads. A prominent .NET web site has offered me a couple of free weeks banner placement and I don't want to waste the opportunity with "get yer ASP.NET training here".

While I know the theory, and regularly take part in creative brainstorms for clients, I am struggling to come up with ideas for myself. Is this a symptom of not having a clear understanding of my own brand or just writers block? Perhaps all the psychology reading I have been doing lately is causing me to overthink it?

Do banners need to be "clever" to work? Something tells me they don't, but on the other hand I don't want something lame and I don't want them to read like DM/Spam pressure sales :S