philana: ah - the reps are telling me you are using far too little weight.
over 15 reps, well... it's kind of a waste of time.
for large muscle groups, no more than 8-10 (12 at the *very* most) and for small groups, 12-15.
such high reps is more a low-grade cardio than it is resistance training - kind of like whatever-her-name-is's much-touted 1000 crunches a day: they're not actually doing anything for her abs but she's burning calories and not eating the entire time she's doing them so that's where she sees the benefit.
me, i've only got one set of 10lb dumbbells. for bicep curls, overhead tricep extension, and upright shoulder press i do 15reps but bec the weight is so light, i do them verrrrrrrry very slowly while making sure to keep my muscles flexed as much as possible the entire time. it's one way to build big muscles - same way ppl who milk cows and goats by hand get bowling-pin forearms even though they're not using any weight.
for the lunges, you might try to up the ante a bit: switch to dip-lunges. instead of "step forward - dip - step back", try "step forward - dip - straighten up - dip - repeat until all reps are done on one leg and then switch to the other".
this video shows a more advanced technique, where the trailing leg is resting up on a bench (increases the intensity yet again) but you can just rest your foot on the floor:
http://www.youtube.com/watch?v=eQUMw4JgMN0
the bonus to this technique is you're WAY less likely to injure yourself (personal experience: lost my balance doing a weighted lunge with a 45lb barbell and ended up on crutches for 6wks)
(and in case you're wondering, no - using heavier weights will not make you blow up like arnold schwarzenegger - that's a man thing; women have to actually work for that and frequently need steroids to get that uber-built IFBB Pro look)