Spec writing, drafting/document prep, planning/schematics, program management, master planning, construction administration, etc....all sorts of specialties within the different field sectors.  I personally specialize in departmental hospital renovations with a particular expertise in pharmacies/cleanrooms.  Not much design, but extremely difficult and technical.  

forensic architecture, which involves diagnosing and analyzing building failures, like structural collapse, fire damage, etc.  Presumably you are a professional professional witness.  Probably not a lot of openings, but in a litigious society it could offer real job security.  :-)

I always thought forensics would be fun. 

ADA, historic preservation, renovations, interiors (for example, tenant spaces in multi-use buildings), exterior envelope. Can specialize by building type too: banks, schools, retail, healthcare, hospitality. I specialize in generalizing.

edit to add: Can "specialize" in expedience, responsiveness, customer service. Or by style.

What can't an architect specialize in? is the question

I always figured forensics was more of an engineer's domain (especially when you're looking at structural collapse, fire damage, etc.).

Add to the list of specializations: Building codes, building science, document QAQC, training/mentoring aspiring architects, passive design, and green washing ... er ... I mean sustainability.

EI, architects are better for forensics because they unserstand all parts of the building. this is not to say engineers are not brought in to subatantiate discoveries and analysis.......other items - renderings and if you leave the field with your education - construction management, ownership, facilities,etc....

...adaptive reuse (is that an official category now? developers would say so), owner's rep, specialty contractor (i.e. a design-build or design-assist entity), a consulting shop (even if it's mostly engineering you can be an architectural unicorn), adjunct professor journeyman (tenure doesn't exist anymore), sell stamp on Craigslist, etc...

Forensic architecture.... mostly dead to us now.  That was my specialty.  Blame the AIA for marketing "we make it pretty" instead of "master builder".  So engineers swooped in with "we make it work".   That is the public impression.....  So regardless that we have the training and often the authority on the job site to accept or reject work, you'll struggle getting work in that dying market.  Don't blame the attorney's, blame the possible jury and who they'll trust more.  

Urban Planning; Also dead without a urban planning degree (I know two architects who have gone back to school because urban planning is what they want to do).

I shut down my business and transitioned to quality control / quality assurance in a biggish firm to help them stay out of lawsuits.  It's sort of a specialty.

There's also Historic Architecture.  Very niche and hard to find projects without covering a very large region.  Fits right in with that adaptive reuse.

There are tenant improvement (TI) specialist.  All they really do is set themselves up with major property management firms.  Both residential and commercial.

There are Design/Build architects; Usually in the direct employ of the contractor or developer.

There are Owner Representatives; That is what my licensed sister does.  She oversee's architects and projects for a University.  Along those lines are corporate architects; Take your major brand labels, and they most likely have a design team somewhere.  They oversee the local architect as the brand representative.

There are teachers; My Brother inlaw is a professor in architecture.

I know one who transitioned to computer gaming designing the environments; Didn't last long.

I know one who got into stage set designs.  More of a hobby that bloomed.  He also designs displays; like museum stuff.  Very niche.

I know one (she's really a stay at home mom) that does landscape "built stuff" like trellis's, pavillions, follies, etc. for various agencies (think botanical garden stuff).

I know a lot who switched over to product reps. 

mightyaa the architect I work for that does that work is 73....

Ya, my Dad did that too, he's now 78 (gives you a clue how old I am), and has dual licenses (arch & struct eng)... It's how I got in it by assisting, then being the expert on small ones to build the CV until I was the primary expert on larger cases.  I'd been doing those investigations even as a kid just holding the dumb end of a tape and crawling into spaces my Dad couldn't to photographic and document.  

The insurance stuff was so much cooler btw.   I actually miss that stuff most.  Explosion damage, wind, fire, water (mostly snow), and weird combo stuff like baseball hail pitched by a twister into buildings...  actually seeing firecuts work or how most the damage after a fire is really the FD putting it out.  I've seen things like a house filled with water then frozen into a solid block or a microburst lift a warehouse roof and set it back down 4" from where it should be, or steel beams expand in a fire, blow holes through walls, and rip connections or a townhome in the middle blowing up and how the structure telegraphs those forces to the rest of the units.  Really neat stuff to really investigate and see how buildings perform in the extremes.  If you were into blowing up stuff as a kid, you'd love this.

The litigation wasn't nearly as interesting.

Still looking for a way I can specialize in tiki bars and camping.

I did an internship with a 73 year engineer who did investigations for failures. Many of the things we documented as poor design and detailing were done by an architecture firm I later interned for. Whole new levels of awkwardness were thus achieved. Talk about needing to learn to keep your mouth shut... sometimes I'm a slow learner.

Still looking for a way I can specialize in tiki bars and camping.

There's that luxury camping thing going on.  I know a job super who landed a gig in Belize where he built treehouse lodgings for sort of camping type resort you got to by horseback.  It was basically a traveling stay sort of deal so the patrons would stay at this camp for a day, then travel and go to the next and so on.

Have a old family friend that did the extreme ski tour stuff.  They'd build cabins and get there by snowcats then hit the backwoods or helicopter to the bowl.  He was a guide...  

Sort of a beachbum type lifestyle though.  Was super envious of these guys when I was young.  But now that I'm older?  Seeing that family friend live out of the back of his landscaping business warehouse, no stable income, no family, no real life and a body that reflects years of abuse... not so cool.