For a birthday card, I want to do some 3D extruded lettters. Can inkscape do that?
Thanks for any tips or links to tutorials or plugins!

Hi.

Check these:
http://www.inkscapeforum.com/viewtopic.php?f=5&t=18423
and
http://www.inkscapeforum.com/viewtopic.php?f=5&t=18540.

It depends on your needs, inkscape can "extrude" sharp characters like "E" easily, but for rounded letters like "B" you may need some manual reworking. For a clean file, it can take quite some time.

As discussed in the topic above, you can make 3D letters with a 3D programs in no time.

how about this tutorial ?

https://www.youtube.com/watch?v=vacjO8AbLDg

Thanks for the tips. I'm having trouble extruding in Inkscape.

What kind of 3D program can I use with Ubuntu to do this? Can you suggest one please?

It's not Inkscape, but maybe this is a solution: www.flamingtext.com ?
Terms of use state: "Personal or Academic Use: Provided you uphold the terms in this agreement, you are licensed to use all logos and graphics generated by this website in personal and academic work including emails, websites, blogs, birthday cards and/or any other non-commercial projects. Under this personal and academic use license you agree to make no claim that you created any of the graphics generated by this website, or any derivation of the graphics."

(I'm not affiliated to flamingtext in any way, just happen to know it...)

Most of those at that site looks to have only some fancy filters added.
For example this topic is also related.

For 3D modelling I would use blender.
https://www.blender.org/manual/about/install/linux.html?highlight=ubuntu

Now it can also render to svg-s, if vector svg is a must.
http://goinkscape.com/use-blender-freestyle-to-export-svg-artwork/

Just want to say thanks to all, especially to Espermachine, that youtube link is great, just took me a while to follow what he was doing! I can't figure out what language he is muttering in! Now I can do it!

That should be a macro, now, if only I knew how to do that!