Ok, so my disclaimer up front is that I have a daughter and a sister, two nieces and five (much younger than me) female cousins... so, my advice should be taken as coming from someone with almost no experience with boys.
Having said that, is there something that he might be peripherally interested in that you could capitalize on during this (almost) last chance to get him something brain stimulating (instead of just another video game or music or something that he doesn't have to interact with)?
The examples I thought of were:
Something like a science kit, in an area he enjoys. Some examples are at Home Science Tools: http://www.hometrainingtools.com/catalog/special-categori...
Many aren't very expensive and you can find something in various areas of interest like cars, how things work, solar system stuff and even a rock tumbler (my husband loved finding rough rocks as a kid and tumbling them up all shiney and led to his interest in geology).
This site has an electricity kit:
http://thenaturestore.com/sciencekits.htm
which can always be fun.
Also, if he likes to read, there's the "Oh Yikes!" book
http://shopping.discovery.com/product-61701.html at the Discovery Channel store (they have a "boy 8-12" gift link) or the "Oh Yuck!" book http://shopping.discovery.com/product-61701.html - both of these are books that cover icky topics that boys would find interesting.. the Yikes book covers experiments gone wrong/monumentally bad ideas, etc. These are geared to 9-12 year olds, though, so depending on how mature he is at this point, he may find these to be too "young".
Finally, I think there are several sites online that will help you put together a small construction project as a gift (birdhouse, small bench, etc) that your stepson and his dad could construct together - promotes dad & son time. I even think Home Depot has some of these.
Anyway, that's all I could think of... hope they make sense and at the very least spur a thought that gets you to the perfect gift! Happy hunting.
P.
