I thought I'd be a positive member of the TWHL community and offer some ideas for those who are stuck on an idea for a mod or just want to do some side project to blow off some time. I'm still learning how to map, so making these ideas reality on my own time isn't likely to happen (or turn out pretty). :
1. "Stupid HL: Escape From Purple Mesa" - This mod is all about the funny. You are Goober Freeman, hired to work at Purple Mesa by Adminstrator McBoingBoing (PM's version of the G-Man). After attending a lecture on the new equation proving the viscosity of Cheez Whiz, hippies from People For the Ethical Treatment of Aliems (parody of the morons of PETA. PETAliems' site can be found here: http://www.stopalienautopsies.org/ . I didn't make that), attack the base, mistaking PM for a newly rebuilt BMRF. Now that things have gone babooshka, the Half-Life Plot Cliches of Doom have decided that you are the only one to save the mentally incapacitated residents of PM and be a hero or something. If there were a Richter Scale for funny, this mod would be a 10.5
More info can be found in these files: http://savefile.com/projects.php?pid=971633 (One's a script, the other's an unfinished story I started on a day or two ago. I've stopped at the point where Goober's booted out of the PM Trolley and wanders through the employee entrance.) The script is just the basic jist of it. I planned to have more funny stuff, where the aliens come in and make fools of themselves. That way, I'd be able to have a sequel where Goober and his new Houndeye buddy Fred set out on an adventure to get Aliem Food from Petco and to find out who really did eat all the donuts.
(PS: I misspelled "Aliems" on purpose)
2. "Lost on Xen" - I started thinking (while I was out on a walk) that this mod wouldn't be possible due to Half-Life's odd time constraints, unless the LoX story is set hours before the RC incident.
But anyway:
You are Nathan Freeman, 8-year-old nephew to the great Gordon. After Christmas your parents stuck you with your Uncle while they were on their zillionth honeymoon. Just Uncle Freeman's luck. Unfortunatly, despite your constant prodding to watch Uncle Freeman do his work, he sticks you with an off-duty Barney in the lunch hall (not only because he's concerned for your safety, but he just doesn't like you.) Of course, being the nosy little bastard that you are, you wander off and began to explore the outer reaches of BMRF, eventually finding an odd-looking machine (a big teleporter), hopping into it, and getting your prepubescent keister hauled off to Xen. Fortunatly for you, there's a rebel faction of Vortigaunts in the area who are happy to take you in after a nasty runin with an Alien Grunt. After that, epic battles ensue and you eventually find yourself back on Earth. To what? ...I haven't gotten that far yet.
I also have an idea for a mappack involving a Salvador Dali-esque nightmare (as in REM), but I might end up doing that one.
So, if that doesn't really get your creative mod juices flowing, I don't know what will. Have fun!